Cross-hypervisor live mount of backed up virtual machine data

ABSTRACT

Illustrative systems and methods enable a virtual machine (“VM”) to be powered up at any hypervisor regardless of hypervisor type, based on live-mounting VM data that was originally backed up into a hypervisor-independent format by a block-level backup operation. Afterwards, the backed up VM executes anywhere anytime without needing to find a hypervisor that is the same as or compatible with the original source VM&#39;s hypervisor. The backed up VM payload data is rendered portable to any virtualized platform. Thus, a VM can be powered up at one or more test stations, data center or cloud recovery environments, and/or backup appliances, without the prior-art limitations of finding a same/compatible hypervisor for accessing and using backed up VM data. An illustrative media agent maintains cache storage that acts as a way station for data blocks retrieved from an original backup copy, and stores data blocks written by the live-mounted VM.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.16/262,721 filed on Jan. 30, 2019. Any and all applications for which aforeign or domestic priority claim is identified in the Application DataSheet of the present application are hereby incorporated by reference intheir entireties under 37 CFR 1.57. This application is related to U.S.patent application Ser. No. 16/262,753 filed on Jan. 30, 2019 with thetitle of “Cross-Hypervisor Live-Mount Of Backed Up Virtual Machine Data,Including Management Of Cache Storage For Virtual Machine Data” which isincorporated by reference in its entirety herein

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentand/or the patent disclosure as it appears in the United States Patentand Trademark Office patent file and/or records, but otherwise reservesall copyrights whatsoever.

BACKGROUND

Businesses recognize the commercial value of their data and seekreliable, cost-effective ways to protect the information stored on theircomputer networks while minimizing impact on productivity. A companymight back up critical computing systems such as databases, fileservers, web servers, virtual machines, and so on as part of a scheduleor on demand. Enterprises increasingly view their stored data as avaluable asset and look for solutions that leverage their data.Solutions are needed for ensuring the integrity and viability of backedup data for use in disaster recovery, for testing and debugging, andmore generally, for access from anywhere at any time.

SUMMARY

The present inventors devised an approach that seamlessly enables avirtual machine (“VM”) to be powered up at any hypervisor regardless ofhypervisor type, based on live-mounting VM data that was originallybacked up by a block-level backup operation into ahypervisor-independent format. Accordingly, after the original backupoperation, the backed up VM can execute anywhere anytime without needingto find a hypervisor that is the same as or compatible with the originalsource VM's hypervisor. The backed up VM payload data is renderedportable to any virtualized platform. Thus, a VM can be powered up atone or more test stations, data centers, cloud recovery environments,and/or backup appliances, without the prior-art limitations of finding asame/compatible hypervisor to access and use backed up VM data. Thefeature is referred to herein as “cross-hypervisor live-mount” as ashorthand for the collective functionality described herein.

An illustrative data agent is enhanced to orchestrate and coordinate thedescribed feature. An illustrative media agent hosts and maintains cachestorage that acts as a way station for data blocks retrieved from theoriginal backup copy, and further acts as a repository for data blockswritten by the live-mounted VM. An illustrative storage manager, whichis also responsible for managing storage operations in the illustrativedata storage management system, is enhanced to initiate across-hypervisor live-mount operation when it determines that a certainVM backup copy is suitable for the operation.

Illustratively, the cache storage is exposed/exported and mounted to thetarget VM's hypervisor as native storage. The hypervisor creates avirtual disk within the cache storage for each of its target VMs. Thecache storage is configured as a Network File System (“NFS”) export,Internet Small Computer Systems Interface (“iSCSI”) target, FibreChannel (“FC”), and/or any other storage technologies that are suitableto the hypervisor hosting the target VMs. The illustrative media agentmanages the cache storage, purging least-used data blocks as needed tofree up cache storage space, yet keeping frequently-read data blocks anddata blocks written by the target VMs intact in the cache storage. To dothis, the illustrative media agent keeps track of data block activitywithin the cache storage and also manages thresholds and sizeflexibility to make room as needed, e.g., for new VM backup copies beingadded, for additional virtual disks, etc.

The illustrative architecture is suitable for a variety ofimplementations, including data center, cloud, and/or integrated backupappliances. An illustrative backup appliance comprises the media agent,cache storage resources, the target hypervisor, and target VMs. Theillustrative architecture also enables the live-mounting of the same VMbackup copy to several different target VMs, each one operatingindependently of the others but running off the same backup data. Thisapproach is especially advantageous, because according to theillustrative cross-hypervisor live mount feature, the VM backup copy isnot restored in its entirety and thus the solution is space-efficientand enables the target VMs to start up relatively quickly withoutwaiting for a full restore to complete.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram illustrating an exemplary informationmanagement system.

FIG. 1B is a detailed view of a primary storage device, a secondarystorage device, and some examples of primary data and secondary copydata.

FIG. 1C is a block diagram of an exemplary information management systemincluding a storage manager, one or more data agents, and one or moremedia agents.

FIG. 1D is a block diagram illustrating a scalable informationmanagement system.

FIG. 1E illustrates certain secondary copy operations according to anexemplary storage policy.

FIGS. 1F-1H are block diagrams illustrating suitable data structuresthat may be employed by the information management system.

FIG. 2A illustrates a system and technique for synchronizing primarydata to a destination such as a failover site using secondary copy data.

FIG. 2B illustrates an information management system architectureincorporating use of a network file system (NFS) protocol forcommunicating between the primary and secondary storage subsystems.

FIG. 2C is a block diagram of an example of a highly scalable manageddata pool architecture.

FIG. 3 is a block diagram illustrating some salient portions of a system300 for cross-hypervisor live-mount of backed up virtual machine dataaccording to an illustrative embodiment of the present invention.

FIG. 4 is a block diagram illustrating some salient details of system300, including storage manager 440 and some components of backup proxymachine 306.

FIG. 5 is a block diagram illustrating some salient details of system300 configured with a plurality of distinct target virtual machineslive-mounted to the same virtual machine backup copy.

FIG. 6 is a block diagram illustrating some salient portions of system300 configured to operate within a cloud computing environment 690.

FIG. 7 is a block diagram illustrating some salient portions of system300 configured to operate within a data storage management appliance790.

FIG. 8 depicts some salient operations of a method 800 according to anillustrative embodiment of the present invention.

FIG. 9 depicts some salient operations of a method 900 according to anillustrative embodiment of the present invention.

FIG. 10 depicts some salient operations of a method 900 continued fromFIG. 9.

FIG. 11 depicts some salient operations of a method 1100 according to anillustrative embodiment of the present invention.

DETAILED DESCRIPTION

Detailed descriptions and examples of systems and methods according toone or more illustrative embodiments of the present invention may befound in the section entitled CROSS-HYPERVISOR LIVE-MOUNT OF BACKED UPVIRTUAL MACHINE DATA, as well as in the section entitled ExampleEmbodiments, and also in FIGS. 3-11 herein. Furthermore, components andfunctionality for cross-hypervisor live-mount of backed up virtualmachine data may be configured and/or incorporated into informationmanagement systems such as those described herein in FIGS. 1A-1H and2A-2C.

Various embodiments described herein are intimately tied to, enabled by,and would not exist except for, computer technology. For example,cross-hypervisor live-mount of backed up virtual machine data describedherein in reference to various embodiments cannot reasonably beperformed by humans alone, without the computer technology upon whichthey are implemented.

Information Management System Overview

With the increasing importance of protecting and leveraging data,organizations simply cannot risk losing critical data. Moreover, runawaydata growth and other modern realities make protecting and managing dataincreasingly difficult. There is therefore a need for efficient,powerful, and user-friendly solutions for protecting and managing dataand for smart and efficient management of data storage. Depending on thesize of the organization, there may be many data production sourceswhich are under the purview of tens, hundreds, or even thousands ofindividuals. In the past, individuals were sometimes responsible formanaging and protecting their own data, and a patchwork of hardware andsoftware point solutions may have been used in any given organization.These solutions were often provided by different vendors and had limitedor no interoperability. Certain embodiments described herein addressthese and other shortcomings of prior approaches by implementingscalable, unified, organization-wide information management, includingdata storage management.

FIG. 1A shows one such information management system 100 (or “system100”), which generally includes combinations of hardware and softwareconfigured to protect and manage data and metadata that are generatedand used by computing devices in system 100. System 100 may be referredto in some embodiments as a “storage management system” or a “datastorage management system.” System 100 performs information managementoperations, some of which may be referred to as “storage operations” or“data storage operations,” to protect and manage the data residing inand/or managed by system 100. The organization that employs system 100may be a corporation or other business entity, non-profit organization,educational institution, household, governmental agency, or the like.

Generally, the systems and associated components described herein may becompatible with and/or provide some or all of the functionality of thesystems and corresponding components described in one or more of thefollowing U.S. patents/publications and patent applications assigned toCommvault Systems, Inc., each of which is hereby incorporated byreference in its entirety herein:

-   -   U.S. Pat. No. 7,035,880, entitled “Modular Backup and Retrieval        System Used in Conjunction With a Storage Area Network”;    -   U.S. Pat. No. 7,107,298, entitled “System And Method For        Archiving Objects In An Information Store”;    -   U.S. Pat. No. 7,246,207, entitled “System and Method for        Dynamically Performing Storage Operations in a Computer        Network”;    -   U.S. Pat. No. 7,315,923, entitled “System And Method For        Combining Data Streams In Pipelined Storage Operations In A        Storage Network”;    -   U.S. Pat. No. 7,343,453, entitled “Hierarchical Systems and        Methods for Providing a Unified View of Storage Information”;    -   U.S. Pat. No. 7,395,282, entitled “Hierarchical Backup and        Retrieval System”;    -   U.S. Pat. No. 7,529,782, entitled “System and Methods for        Performing a Snapshot and for Restoring Data”;    -   U.S. Pat. No. 7,617,262, entitled “System and Methods for        Monitoring Application Data in a Data Replication System”;    -   U.S. Pat. No. 7,734,669, entitled “Managing Copies Of Data”;    -   U.S. Pat. No. 7,747,579, entitled “Metabase for Facilitating        Data Classification”;    -   U.S. Pat. No. 8,156,086, entitled “Systems And Methods For        Stored Data Verification”;    -   U.S. Pat. No. 8,170,995, entitled “Method and System for Offline        Indexing of Content and Classifying Stored Data”;    -   U.S. Pat. No. 8,230,195, entitled “System And Method For        Performing Auxiliary Storage Operations”;    -   U.S. Pat. No. 8,285,681, entitled “Data Object Store and Server        for a Cloud Storage Environment, Including Data Deduplication        and Data Management Across Multiple Cloud Storage Sites”;    -   U.S. Pat. No. 8,307,177, entitled “Systems And Methods For        Management Of Virtualization Data”;    -   U.S. Pat. No. 8,364,652, entitled “Content-Aligned, Block-Based        Deduplication”;    -   U.S. Pat. No. 8,578,120, entitled “Block-Level Single        Instancing”;    -   U.S. Pat. No. 8,954,446, entitled “Client-Side Repository in a        Networked Deduplicated Storage System”;    -   U.S. Pat. No. 9,020,900, entitled “Distributed Deduplicated        Storage System”;    -   U.S. Pat. No. 9,098,495, entitled “Application-Aware and Remote        Single Instance Data Management”;    -   U.S. Pat. No. 9,239,687, entitled “Systems and Methods for        Retaining and Using Data Block Signatures in Data Protection        Operations”;    -   U.S. Pat. No. 9,436,555, entitled “Efficient Live-Mount of a        Backed Up Virtual Machine in a Storage Management System”;    -   U.S. Pat. No. 9,633,033, entitled “High Availability Distributed        Deduplicated Storage System”;    -   U.S. Pat. No. 9,710,465, entitled “Efficiently Restoring        Execution of a Backed Up Virtual Machine Based on Coordination        with Virtual-Machine-File-Relocation Operations”;    -   U.S. Pat. No. 9,852,026, entitled “Efficient Application        Recovery in an Information Management System based on a        Pseudo-Storage-Device Driver”;    -   U.S. Pat. Pub. No. 2006/0224846, entitled “System and Method to        Support Single Instance Storage Operations”;    -   U.S. Pat. Pub. No. 2016-0350391, entitled “Replication Using        Deduplicated Secondary Copy Data”;    -   U.S. Pat. Pub. No. 2017-0168903 A1, entitled “Live        Synchronization and Management of Virtual Machines across        Computing and Virtualization Platforms and Using Live        Synchronization to Support Disaster Recovery”;    -   U.S. Pat. Pub. No. 2017-0185488 A1, entitled “Application-Level        Live Synchronization Across Computing Platforms Including        Synchronizing Co-Resident Applications To Disparate Standby        Destinations And Selectively Synchronizing Some Applications And        Not Others”;    -   U.S. Pat. Pub. No. 2017-0192866 A1, entitled “System For        Redirecting Requests After A Secondary Storage Computing Device        Failure”;    -   U.S. Pat. Pub. No. 2017-0235647 A1, entitled “Data Protection        Operations Based on Network Path Information”;    -   U.S. Pat. Pub. No. 2017-0242871 A1, entitled “Data Restoration        Operations Based on Network Path Information”;    -   and    -   U.S. Pat. Pub. No. 2017-0262204 A1, entitled        “Hypervisor-Independent Block-Level Live Browse for Access to        Backed up Virtual Machine (VM) Data and Hypervisor-Free        File-Level Recovery (Block-Level Pseudo-Mount)”.

System 100 includes computing devices and computing technologies. Forinstance, system 100 can include one or more client computing devices102 and secondary storage computing devices 106, as well as storagemanager 140 or a host computing device for it. Computing devices caninclude, without limitation, one or more: workstations, personalcomputers, desktop computers, or other types of generally fixedcomputing systems such as mainframe computers, servers, andminicomputers. Other computing devices can include mobile or portablecomputing devices, such as one or more laptops, tablet computers,personal data assistants, mobile phones (such as smartphones), and othermobile or portable computing devices such as embedded computers, set topboxes, vehicle-mounted devices, wearable computers, etc. Servers caninclude mail servers, file servers, database servers, virtual machineservers, and web servers. Any given computing device comprises one ormore processors (e.g., CPU and/or single-core or multi-core processors),as well as corresponding non-transitory computer memory (e.g.,random-access memory (RAM)) for storing computer programs which are tobe executed by the one or more processors. Other computer memory formass storage of data may be packaged/configured with the computingdevice (e.g., an internal hard disk) and/or may be external andaccessible by the computing device (e.g., network-attached storage, astorage array, etc.). In some cases, a computing device includes cloudcomputing resources, which may be implemented as virtual machines. Forinstance, one or more virtual machines may be provided to theorganization by a third-party cloud service vendor.

In some embodiments, computing devices can include one or more virtualmachine(s) running on a physical host computing device (or “hostmachine”) operated by the organization. As one example, the organizationmay use one virtual machine as a database server and another virtualmachine as a mail server, both virtual machines operating on the samehost machine. A Virtual machine (“VM”) is a software implementation of acomputer that does not physically exist and is instead instantiated inan operating system of a physical computer (or host machine) to enableapplications to execute within the VM's environment, i.e., a VM emulatesa physical computer. AVM includes an operating system and associatedvirtual resources, such as computer memory and processor(s). Ahypervisor operates between the VM and the hardware of the physical hostmachine and is generally responsible for creating and running the VMs.Hypervisors are also known in the art as virtual machine monitors or avirtual machine managers or “VMMs”, and may be implemented in software,firmware, and/or specialized hardware installed on the host machine.Examples of hypervisors include ESX Server, by VMware, Inc. of PaloAlto, Calif.; Microsoft Virtual Server and Microsoft Windows ServerHyper-V, both by Microsoft Corporation of Redmond, Wash.; Sun xVM byOracle America Inc. of Santa Clara, Calif.; and Xen by Citrix Systems,Santa Clara, Calif. The hypervisor provides resources to each virtualoperating system such as a virtual processor, virtual memory, a virtualnetwork device, and a virtual disk. Each virtual machine has one or moreassociated virtual disks. The hypervisor typically stores the data ofvirtual disks in files on the file system of the physical host machine,called virtual machine disk files (“VMDK” in VMware lingo) or virtualhard disk image files (in Microsoft lingo). For example, VMware's ESXServer provides the Virtual Machine File System (VMFS) for the storageof virtual machine disk files. A virtual machine reads data from andwrites data to its virtual disk much the way that a physical machinereads data from and writes data to a physical disk. Examples oftechniques for implementing information management in a cloud computingenvironment are described in U.S. Pat. No. 8,285,681. Examples oftechniques for implementing information management in a virtualizedcomputing environment are described in U.S. Pat. No. 8,307,177.

Information management system 100 can also include electronic datastorage devices, generally used for mass storage of data, including,e.g., primary storage devices 104 and secondary storage devices 108.Storage devices can generally be of any suitable type including, withoutlimitation, disk drives, storage arrays (e.g., storage-area network(SAN) and/or network-attached storage (NAS) technology), semiconductormemory (e.g., solid state storage devices), network attached storage(NAS) devices, tape libraries, or other magnetic, non-tape storagedevices, optical media storage devices, combinations of the same, etc.In some embodiments, storage devices form part of a distributed filesystem. In some cases, storage devices are provided in a cloud storageenvironment (e.g., a private cloud or one operated by a third-partyvendor), whether for primary data or secondary copies or both.

Depending on context, the term “information management system” can referto generally all of the illustrated hardware and software components inFIG. 1C, or the term may refer to only a subset of the illustratedcomponents. For instance, in some cases, system 100 generally refers toa combination of specialized components used to protect, move, manage,manipulate, analyze, and/or process data and metadata generated byclient computing devices 102. However, system 100 in some cases does notinclude the underlying components that generate and/or store primarydata 112, such as the client computing devices 102 themselves, and theprimary storage devices 104. Likewise secondary storage devices 108(e.g., a third-party provided cloud storage environment) may not be partof system 100. As an example, “information management system” or“storage management system” may sometimes refer to one or more of thefollowing components, which will be described in further detail below:storage manager, data agent, and media agent.

One or more client computing devices 102 may be part of system 100, eachclient computing device 102 having an operating system and at least oneapplication 110 and one or more accompanying data agents executingthereon; and associated with one or more primary storage devices 104storing primary data 112. Client computing device(s) 102 and primarystorage devices 104 may generally be referred to in some cases asprimary storage subsystem 117.

Client Computing Devices, Clients, and Subclients

Typically, a variety of sources in an organization produce data to beprotected and managed. As just one illustrative example, in a corporateenvironment such data sources can be employee workstations and companyservers such as a mail server, a web server, a database server, atransaction server, or the like. In system 100, data generation sourcesinclude one or more client computing devices 102. A computing devicethat has a data agent 142 installed and operating on it is generallyreferred to as a “client computing device” 102, and may include any typeof computing device, without limitation. A client computing device 102may be associated with one or more users and/or user accounts.

A “client” is a logical component of information management system 100,which may represent a logical grouping of one or more data agentsinstalled on a client computing device 102. Storage manager 140recognizes a client as a component of system 100, and in someembodiments, may automatically create a client component the first timea data agent 142 is installed on a client computing device 102. Becausedata generated by executable component(s) 110 is tracked by theassociated data agent 142 so that it may be properly protected in system100, a client may be said to generate data and to store the generateddata to primary storage, such as primary storage device 104. However,the terms “client” and “client computing device” as used herein do notimply that a client computing device 102 is necessarily configured inthe client/server sense relative to another computing device such as amail server, or that a client computing device 102 cannot be a server inits own right. As just a few examples, a client computing device 102 canbe and/or include mail servers, file servers, database servers, virtualmachine servers, and/or web servers.

Each client computing device 102 may have application(s) 110 executingthereon which generate and manipulate the data that is to be protectedfrom loss and managed in system 100. Applications 110 generallyfacilitate the operations of an organization, and can include, withoutlimitation, mail server applications (e.g., Microsoft Exchange Server),file system applications, mail client applications (e.g., MicrosoftExchange Client), database applications or database management systems(e.g., SQL, Oracle, SAP, Lotus Notes Database), word processingapplications (e.g., Microsoft Word), spreadsheet applications, financialapplications, presentation applications, graphics and/or videoapplications, browser applications, mobile applications, entertainmentapplications, and so on. Each application 110 may be accompanied by anapplication-specific data agent 142, though not all data agents 142 areapplication-specific or associated with only application. A file managerapplication, e.g., Microsoft Windows Explorer, may be considered anapplication 110 and may be accompanied by its own data agent 142. Clientcomputing devices 102 can have at least one operating system (e.g.,Microsoft Windows, Mac OS X, iOS, IBM z/OS, Linux, other Unix-basedoperating systems, etc.) installed thereon, which may support or hostone or more file systems and other applications 110. In someembodiments, a virtual machine that executes on a host client computingdevice 102 may be considered an application 110 and may be accompaniedby a specific data agent 142 (e.g., virtual server data agent).

Client computing devices 102 and other components in system 100 can beconnected to one another via one or more electronic communicationpathways 114. For example, a first communication pathway 114 maycommunicatively couple client computing device 102 and secondary storagecomputing device 106; a second communication pathway 114 maycommunicatively couple storage manager 140 and client computing device102; and a third communication pathway 114 may communicatively couplestorage manager 140 and secondary storage computing device 106, etc.(see, e.g., FIG. 1A and FIG. 1C). A communication pathway 114 caninclude one or more networks or other connection types including one ormore of the following, without limitation: the Internet, a wide areanetwork (WAN), a local area network (LAN), a Storage Area Network (SAN),a Fibre Channel (FC) connection, a Small Computer System Interface(SCSI) connection, a virtual private network (VPN), a token ring orTCP/IP based network, an intranet network, a point-to-point link, acellular network, a wireless data transmission system, a two-way cablesystem, an interactive kiosk network, a satellite network, a broadbandnetwork, a baseband network, a neural network, a mesh network, an ad hocnetwork, other appropriate computer or telecommunications networks,combinations of the same or the like. Communication pathways 114 in somecases may also include application programming interfaces (APIs)including, e.g., cloud service provider APIs, virtual machine managementAPIs, and hosted service provider APIs. The underlying infrastructure ofcommunication pathways 114 may be wired and/or wireless, analog and/ordigital, or any combination thereof; and the facilities used may beprivate, public, third-party provided, or any combination thereof,without limitation.

A “subclient” is a logical grouping of all or part of a client's primarydata 112. In general, a subclient may be defined according to how thesubclient data is to be protected as a unit in system 100. For example,a subclient may be associated with a certain storage policy. A givenclient may thus comprise several subclients, each subclient associatedwith a different storage policy. For example, some files may form afirst subclient that requires compression and deduplication and isassociated with a first storage policy. Other files of the client mayform a second subclient that requires a different retention schedule aswell as encryption, and may be associated with a different, secondstorage policy. As a result, though the primary data may be generated bythe same application 110 and may belong to one given client, portions ofthe data may be assigned to different subclients for distinct treatmentby system 100. More detail on subclients is given in regard to storagepolicies below.

Primary Data and Exemplary Primary Storage Devices

Primary data 112 is generally production data or “live” data generatedby the operating system and/or applications 110 executing on clientcomputing device 102. Primary data 112 is generally stored on primarystorage device(s) 104 and is organized via a file system operating onthe client computing device 102. Thus, client computing device(s) 102and corresponding applications 110 may create, access, modify, write,delete, and otherwise use primary data 112. Primary data 112 isgenerally in the native format of the source application 110. Primarydata 112 is an initial or first stored body of data generated by thesource application 110. Primary data 112 in some cases is createdsubstantially directly from data generated by the corresponding sourceapplication 110. It can be useful in performing certain tasks toorganize primary data 112 into units of different granularities. Ingeneral, primary data 112 can include files, directories, file systemvolumes, data blocks, extents, or any other hierarchies or organizationsof data objects. As used herein, a “data object” can refer to (i) anyfile that is currently addressable by a file system or that waspreviously addressable by the file system (e.g., an archive file),and/or to (ii) a subset of such a file (e.g., a data block, an extent,etc.). Primary data 112 may include structured data (e.g., databasefiles), unstructured data (e.g., documents), and/or semi-structureddata. See, e.g., FIG. 1B.

It can also be useful in performing certain functions of system 100 toaccess and modify metadata within primary data 112. Metadata generallyincludes information about data objects and/or characteristicsassociated with the data objects. For simplicity herein, it is to beunderstood that, unless expressly stated otherwise, any reference toprimary data 112 generally also includes its associated metadata, butreferences to metadata generally do not include the primary data.Metadata can include, without limitation, one or more of the following:the data owner (e.g., the client or user that generates the data), thelast modified time (e.g., the time of the most recent modification ofthe data object), a data object name (e.g., a file name), a data objectsize (e.g., a number of bytes of data), information about the content(e.g., an indication as to the existence of a particular search term),user-supplied tags, to/from information for email (e.g., an emailsender, recipient, etc.), creation date, file type (e.g., format orapplication type), last accessed time, application type (e.g., type ofapplication that generated the data object), location/network (e.g., acurrent, past or future location of the data object and network pathwaysto/from the data object), geographic location (e.g., GPS coordinates),frequency of change (e.g., a period in which the data object ismodified), business unit (e.g., a group or department that generates,manages or is otherwise associated with the data object), aginginformation (e.g., a schedule, such as a time period, in which the dataobject is migrated to secondary or long term storage), boot sectors,partition layouts, file location within a file folder directorystructure, user permissions, owners, groups, access control lists(ACLs), system metadata (e.g., registry information), combinations ofthe same or other similar information related to the data object. Inaddition to metadata generated by or related to file systems andoperating systems, some applications 110 and/or other components ofsystem 100 maintain indices of metadata for data objects, e.g., metadataassociated with individual email messages. The use of metadata toperform classification and other functions is described in greaterdetail below.

Primary storage devices 104 storing primary data 112 may be relativelyfast and/or expensive technology (e.g., flash storage, a disk drive, ahard-disk storage array, solid state memory, etc.), typically to supporthigh-performance live production environments. Primary data 112 may behighly changeable and/or may be intended for relatively short termretention (e.g., hours, days, or weeks). According to some embodiments,client computing device 102 can access primary data 112 stored inprimary storage device 104 by making conventional file system calls viathe operating system. Each client computing device 102 is generallyassociated with and/or in communication with one or more primary storagedevices 104 storing corresponding primary data 112. A client computingdevice 102 is said to be associated with or in communication with aparticular primary storage device 104 if it is capable of one or moreof: routing and/or storing data (e.g., primary data 112) to the primarystorage device 104, coordinating the routing and/or storing of data tothe primary storage device 104, retrieving data from the primary storagedevice 104, coordinating the retrieval of data from the primary storagedevice 104, and modifying and/or deleting data in the primary storagedevice 104. Thus, a client computing device 102 may be said to accessdata stored in an associated storage device 104.

Primary storage device 104 may be dedicated or shared. In some cases,each primary storage device 104 is dedicated to an associated clientcomputing device 102, e.g., a local disk drive. In other cases, one ormore primary storage devices 104 can be shared by multiple clientcomputing devices 102, e.g., via a local network, in a cloud storageimplementation, etc. As one example, primary storage device 104 can be astorage array shared by a group of client computing devices 102, such asEMC Clariion, EMC Symmetrix, EMC Celerra, Dell EqualLogic, IBM XIV,NetApp FAS, HP EVA, and HP 3PAR.

System 100 may also include hosted services (not shown), which may behosted in some cases by an entity other than the organization thatemploys the other components of system 100. For instance, the hostedservices may be provided by online service providers. Such serviceproviders can provide social networking services, hosted email services,or hosted productivity applications or other hosted applications such assoftware-as-a-service (SaaS), platform-as-a-service (PaaS), applicationservice providers (ASPs), cloud services, or other mechanisms fordelivering functionality via a network. As it services users, eachhosted service may generate additional data and metadata, which may bemanaged by system 100, e.g., as primary data 112. In some cases, thehosted services may be accessed using one of the applications 110. As anexample, a hosted mail service may be accessed via browser running on aclient computing device 102.

Secondary Copies and Exemplary Secondary Storage Devices

Primary data 112 stored on primary storage devices 104 may becompromised in some cases, such as when an employee deliberately oraccidentally deletes or overwrites primary data 112. Or primary storagedevices 104 can be damaged, lost, or otherwise corrupted. For recoveryand/or regulatory compliance purposes, it is therefore useful togenerate and maintain copies of primary data 112. Accordingly, system100 includes one or more secondary storage computing devices 106 and oneor more secondary storage devices 108 configured to create and store oneor more secondary copies 116 of primary data 112 including itsassociated metadata. The secondary storage computing devices 106 and thesecondary storage devices 108 may be referred to as secondary storagesubsystem 118.

Secondary copies 116 can help in search and analysis efforts and meetother information management goals as well, such as: restoring dataand/or metadata if an original version is lost (e.g., by deletion,corruption, or disaster); allowing point-in-time recovery; complyingwith regulatory data retention and electronic discovery (e-discovery)requirements; reducing utilized storage capacity in the productionsystem and/or in secondary storage; facilitating organization and searchof data; improving user access to data files across multiple computingdevices and/or hosted services; and implementing data retention andpruning policies.

A secondary copy 116 can comprise a separate stored copy of data that isderived from one or more earlier-created stored copies (e.g., derivedfrom primary data 112 or from another secondary copy 116). Secondarycopies 116 can include point-in-time data, and may be intended forrelatively long-term retention before some or all of the data is movedto other storage or discarded. In some cases, a secondary copy 116 maybe in a different storage device than other previously stored copies;and/or may be remote from other previously stored copies. Secondarycopies 116 can be stored in the same storage device as primary data 112.For example, a disk array capable of performing hardware snapshotsstores primary data 112 and creates and stores hardware snapshots of theprimary data 112 as secondary copies 116. Secondary copies 116 may bestored in relatively slow and/or lower cost storage (e.g., magnetictape). A secondary copy 116 may be stored in a backup or archive format,or in some other format different from the native source applicationformat or other format of primary data 112.

Secondary storage computing devices 106 may index secondary copies 116(e.g., using a media agent 144), enabling users to browse and restore ata later time and further enabling the lifecycle management of theindexed data. After creation of a secondary copy 116 that representscertain primary data 112, a pointer or other location indicia (e.g., astub) may be placed in primary data 112, or be otherwise associated withprimary data 112, to indicate the current location of a particularsecondary copy 116. Since an instance of a data object or metadata inprimary data 112 may change over time as it is modified by application110 (or hosted service or the operating system), system 100 may createand manage multiple secondary copies 116 of a particular data object ormetadata, each copy representing the state of the data object in primarydata 112 at a particular point in time. Moreover, since an instance of adata object in primary data 112 may eventually be deleted from primarystorage device 104 and the file system, system 100 may continue tomanage point-in-time representations of that data object, even thoughthe instance in primary data 112 no longer exists. For virtual machines,the operating system and other applications 110 of client computingdevice(s) 102 may execute within or under the management ofvirtualization software (e.g., a VMM), and the primary storage device(s)104 may comprise a virtual disk created on a physical storage device.System 100 may create secondary copies 116 of the files or other dataobjects in a virtual disk file and/or secondary copies 116 of the entirevirtual disk file itself (e.g., of an entire .vmdk file).

Secondary copies 116 are distinguishable from corresponding primary data112. First, secondary copies 116 can be stored in a different formatfrom primary data 112 (e.g., backup, archive, or other non-nativeformat). For this or other reasons, secondary copies 116 may not bedirectly usable by applications 110 or client computing device 102(e.g., via standard system calls or otherwise) without modification,processing, or other intervention by system 100 which may be referred toas “restore” operations. Secondary copies 116 may have been processed bydata agent 142 and/or media agent 144 in the course of being created(e.g., compression, deduplication, encryption, integrity markers,indexing, formatting, application-aware metadata, etc.), and thussecondary copy 116 may represent source primary data 112 withoutnecessarily being exactly identical to the source.

Second, secondary copies 116 may be stored on a secondary storage device108 that is inaccessible to application 110 running on client computingdevice 102 and/or hosted service. Some secondary copies 116 may be“offline copies,” in that they are not readily available (e.g., notmounted to tape or disk). Offline copies can include copies of data thatsystem 100 can access without human intervention (e.g., tapes within anautomated tape library, but not yet mounted in a drive), and copies thatthe system 100 can access only with some human intervention (e.g., tapeslocated at an offsite storage site).

Using Intermediate Devices for Creating Secondary Copies—SecondaryStorage Computing Devices

Creating secondary copies can be challenging when hundreds or thousandsof client computing devices 102 continually generate large volumes ofprimary data 112 to be protected. Also, there can be significantoverhead involved in the creation of secondary copies 116. Moreover,specialized programmed intelligence and/or hardware capability isgenerally needed for accessing and interacting with secondary storagedevices 108. Client computing devices 102 may interact directly with asecondary storage device 108 to create secondary copies 116, but in viewof the factors described above, this approach can negatively impact theability of client computing device 102 to serve/service application 110and produce primary data 112. Further, any given client computing device102 may not be optimized for interaction with certain secondary storagedevices 108.

Thus, system 100 may include one or more software and/or hardwarecomponents which generally act as intermediaries between clientcomputing devices 102 (that generate primary data 112) and secondarystorage devices 108 (that store secondary copies 116). In addition tooff-loading certain responsibilities from client computing devices 102,these intermediate components provide other benefits. For instance, asdiscussed further below with respect to FIG. 1D, distributing some ofthe work involved in creating secondary copies 116 can enhancescalability and improve system performance. For instance, usingspecialized secondary storage computing devices 106 and media agents 144for interfacing with secondary storage devices 108 and/or for performingcertain data processing operations can greatly improve the speed withwhich system 100 performs information management operations and can alsoimprove the capacity of the system to handle large numbers of suchoperations, while reducing the computational load on the productionenvironment of client computing devices 102. The intermediate componentscan include one or more secondary storage computing devices 106 as shownin FIG. 1A and/or one or more media agents 144. Media agents arediscussed further below (e.g., with respect to FIGS. 1C-1E). Thesespecial-purpose components of system 100 comprise specialized programmedintelligence and/or hardware capability for writing to, reading from,instructing, communicating with, or otherwise interacting with secondarystorage devices 108.

Secondary storage computing device(s) 106 can comprise any of thecomputing devices described above, without limitation. In some cases,secondary storage computing device(s) 106 also include specializedhardware componentry and/or software intelligence (e.g., specializedinterfaces) for interacting with certain secondary storage device(s) 108with which they may be specially associated.

To create a secondary copy 116 involving the copying of data fromprimary storage subsystem 117 to secondary storage subsystem 118, clientcomputing device 102 may communicate the primary data 112 to be copied(or a processed version thereof generated by a data agent 142) to thedesignated secondary storage computing device 106, via a communicationpathway 114. Secondary storage computing device 106 in turn may furtherprocess and convey the data or a processed version thereof to secondarystorage device 108. One or more secondary copies 116 may be created fromexisting secondary copies 116, such as in the case of an auxiliary copyoperation, described further below.

Exemplary Primary Data and an Exemplary Secondary Copy

FIG. 1B is a detailed view of some specific examples of primary datastored on primary storage device(s) 104 and secondary copy data storedon secondary storage device(s) 108, with other components of the systemremoved for the purposes of illustration. Stored on primary storagedevice(s) 104 are primary data 112 objects including word processingdocuments 119A-B, spreadsheets 120, presentation documents 122, videofiles 124, image files 126, email mailboxes 128 (and corresponding emailmessages 129A-C), HTML/XML or other types of markup language files 130,databases 132 and corresponding tables or other data structures133A-133C. Some or all primary data 112 objects are associated withcorresponding metadata (e.g., “Meta1-11”), which may include file systemmetadata and/or application-specific metadata. Stored on the secondarystorage device(s) 108 are secondary copy 116 data objects 134A-C whichmay include copies of or may otherwise represent corresponding primarydata 112.

Secondary copy data objects 134A-C can individually represent more thanone primary data object. For example, secondary copy data object 134Arepresents three separate primary data objects 133C, 122, and 129C(represented as 133C′, 122′, and 129C′, respectively, and accompanied bycorresponding metadata Meta11, Meta3, and Meta8, respectively).Moreover, as indicated by the prime mark (′), secondary storagecomputing devices 106 or other components in secondary storage subsystem118 may process the data received from primary storage subsystem 117 andstore a secondary copy including a transformed and/or supplementedrepresentation of a primary data object and/or metadata that isdifferent from the original format, e.g., in a compressed, encrypted,deduplicated, or other modified format. For instance, secondary storagecomputing devices 106 can generate new metadata or other informationbased on said processing, and store the newly generated informationalong with the secondary copies. Secondary copy data object 134Brepresents primary data objects 120, 133B, and 119A as 120′, 133B′, and119A′, respectively, accompanied by corresponding metadata Meta2,Meta10, and Meta1, respectively. Also, secondary copy data object 134Crepresents primary data objects 133A, 119B, and 129A as 133A′, 119B′,and 129A′, respectively, accompanied by corresponding metadata Meta9,Meta5, and Meta6, respectively.

Exemplary Information Management System Architecture

System 100 can incorporate a variety of different hardware and softwarecomponents, which can in turn be organized with respect to one anotherin many different configurations, depending on the embodiment. There arecritical design choices involved in specifying the functionalresponsibilities of the components and the role of each component insystem 100. Such design choices can impact how system 100 performs andadapts to data growth and other changing circumstances. FIG. 1C shows asystem 100 designed according to these considerations and includes:storage manager 140, one or more data agents 142 executing on clientcomputing device(s) 102 and configured to process primary data 112, andone or more media agents 144 executing on one or more secondary storagecomputing devices 106 for performing tasks involving secondary storagedevices 108.

Storage Manager

Storage manager 140 is a centralized storage and/or information managerthat is configured to perform certain control functions and also tostore certain critical information about system 100—hence storagemanager 140 is said to manage system 100. As noted, the number ofcomponents in system 100 and the amount of data under management can belarge. Managing the components and data is therefore a significant task,which can grow unpredictably as the number of components and data scaleto meet the needs of the organization. For these and other reasons,according to certain embodiments, responsibility for controlling system100, or at least a significant portion of that responsibility, isallocated to storage manager 140. Storage manager 140 can be adaptedindependently according to changing circumstances, without having toreplace or re-design the remainder of the system. Moreover, a computingdevice for hosting and/or operating as storage manager 140 can beselected to best suit the functions and networking needs of storagemanager 140. These and other advantages are described in further detailbelow and with respect to FIG. 1D.

Storage manager 140 may be a software module or other application hostedby a suitable computing device. In some embodiments, storage manager 140is itself a computing device that performs the functions describedherein. Storage manager 140 comprises or operates in conjunction withone or more associated data structures such as a dedicated database(e.g., management database 146), depending on the configuration. Thestorage manager 140 generally initiates, performs, coordinates, and/orcontrols storage and other information management operations performedby system 100, e.g., to protect and control primary data 112 andsecondary copies 116. In general, storage manager 140 is said to managesystem 100, which includes communicating with, instructing, andcontrolling in some circumstances components such as data agents 142 andmedia agents 144, etc.

As shown by the dashed arrowed lines 114 in FIG. 1C, storage manager 140may communicate with, instruct, and/or control some or all elements ofsystem 100, such as data agents 142 and media agents 144. In thismanner, storage manager 140 manages the operation of various hardwareand software components in system 100. In certain embodiments, controlinformation originates from storage manager 140 and status as well asindex reporting is transmitted to storage manager 140 by the managedcomponents, whereas payload data and metadata are generally communicatedbetween data agents 142 and media agents 144 (or otherwise betweenclient computing device(s) 102 and secondary storage computing device(s)106), e.g., at the direction of and under the management of storagemanager 140. Control information can generally include parameters andinstructions for carrying out information management operations, suchas, without limitation, instructions to perform a task associated withan operation, timing information specifying when to initiate a task,data path information specifying what components to communicate with oraccess in carrying out an operation, and the like. In other embodiments,some information management operations are controlled or initiated byother components of system 100 (e.g., by media agents 144 or data agents142), instead of or in combination with storage manager 140.

According to certain embodiments, storage manager 140 provides one ormore of the following functions:

-   -   communicating with data agents 142 and media agents 144,        including transmitting instructions, messages, and/or queries,        as well as receiving status reports, index information,        messages, and/or queries, and responding to same;    -   initiating execution of information management operations;    -   initiating restore and recovery operations;    -   managing secondary storage devices 108 and inventory/capacity of        the same;    -   allocating secondary storage devices 108 for secondary copy        operations;    -   reporting, searching, and/or classification of data in system        100;    -   monitoring completion of and status reporting related to        information management operations and jobs;    -   tracking movement of data within system 100;    -   tracking age information relating to secondary copies 116,        secondary storage devices 108, comparing the age information        against retention guidelines, and initiating data pruning when        appropriate;    -   tracking logical associations between components in system 100;    -   protecting metadata associated with system 100, e.g., in        management database 146;    -   implementing job management, schedule management, event        management, alert management, reporting, job history        maintenance, user security management, disaster recovery        management, and/or user interfacing for system administrators        and/or end users of system 100;    -   sending, searching, and/or viewing of log files; and    -   implementing operations management functionality.

Storage manager 140 may maintain an associated database 146 (or “storagemanager database 146” or “management database 146”) ofmanagement-related data and information management policies 148.Database 146 is stored in computer memory accessible by storage manager140. Database 146 may include a management index 150 (or “index 150”) orother data structure(s) that may store: logical associations betweencomponents of the system; user preferences and/or profiles (e.g.,preferences regarding encryption, compression, or deduplication ofprimary data or secondary copies; preferences regarding the scheduling,type, or other aspects of secondary copy or other operations; mappingsof particular information management users or user accounts to certaincomputing devices or other components, etc.; management tasks; mediacontainerization; other useful data; and/or any combination thereof. Forexample, storage manager 140 may use index 150 to track logicalassociations between media agents 144 and secondary storage devices 108and/or movement of data to/from secondary storage devices 108. Forinstance, index 150 may store data associating a client computing device102 with a particular media agent 144 and/or secondary storage device108, as specified in an information management policy 148.

Administrators and others may configure and initiate certain informationmanagement operations on an individual basis. But while this may beacceptable for some recovery operations or other infrequent tasks, it isoften not workable for implementing on-going organization-wide dataprotection and management. Thus, system 100 may utilize informationmanagement policies 148 for specifying and executing informationmanagement operations on an automated basis. Generally, an informationmanagement policy 148 can include a stored data structure or otherinformation source that specifies parameters (e.g., criteria and rules)associated with storage management or other information managementoperations. Storage manager 140 can process an information managementpolicy 148 and/or index 150 and, based on the results, identify aninformation management operation to perform, identify the appropriatecomponents in system 100 to be involved in the operation (e.g., clientcomputing devices 102 and corresponding data agents 142, secondarystorage computing devices 106 and corresponding media agents 144, etc.),establish connections to those components and/or between thosecomponents, and/or instruct and control those components to carry outthe operation. In this manner, system 100 can translate storedinformation into coordinated activity among the various computingdevices in system 100.

Management database 146 may maintain information management policies 148and associated data, although information management policies 148 can bestored in computer memory at any appropriate location outside managementdatabase 146. For instance, an information management policy 148 such asa storage policy may be stored as metadata in a media agent database 152or in a secondary storage device 108 (e.g., as an archive copy) for usein restore or other information management operations, depending on theembodiment. Information management policies 148 are described furtherbelow. According to certain embodiments, management database 146comprises a relational database (e.g., an SQL database) for trackingmetadata, such as metadata associated with secondary copy operations(e.g., what client computing devices 102 and corresponding subclientdata were protected and where the secondary copies are stored and whichmedia agent 144 performed the storage operation(s)). This and othermetadata may additionally be stored in other locations, such as atsecondary storage computing device 106 or on the secondary storagedevice 108, allowing data recovery without the use of storage manager140 in some cases. Thus, management database 146 may comprise dataneeded to kick off secondary copy operations (e.g., storage policies,schedule policies, etc.), status and reporting information aboutcompleted jobs (e.g., status and error reports on yesterday's backupjobs), and additional information sufficient to enable restore anddisaster recovery operations (e.g., media agent associations, locationindexing, content indexing, etc.).

Storage manager 140 may include a jobs agent 156, a user interface 158,and a management agent 154, all of which may be implemented asinterconnected software modules or application programs. These aredescribed further below.

Jobs agent 156 in some embodiments initiates, controls, and/or monitorsthe status of some or all information management operations previouslyperformed, currently being performed, or scheduled to be performed bysystem 100. A job is a logical grouping of information managementoperations such as daily storage operations scheduled for a certain setof subclients (e.g., generating incremental block-level backup copies116 at a certain time every day for database files in a certaingeographical location). Thus, jobs agent 156 may access informationmanagement policies 148 (e.g., in management database 146) to determinewhen, where, and how to initiate/control jobs in system 100.

Storage Manager User Interfaces

User interface 158 may include information processing and displaysoftware, such as a graphical user interface (GUI), an applicationprogram interface (API), and/or other interactive interface(s) throughwhich users and system processes can retrieve information about thestatus of information management operations or issue instructions tostorage manager 140 and other components. Via user interface 158, usersmay issue instructions to the components in system 100 regardingperformance of secondary copy and recovery operations. For example, auser may modify a schedule concerning the number of pending secondarycopy operations. As another example, a user may employ the GUI to viewthe status of pending secondary copy jobs or to monitor the status ofcertain components in system 100 (e.g., the amount of capacity left in astorage device). Storage manager 140 may track information that permitsit to select, designate, or otherwise identify content indices,deduplication databases, or similar databases or resources or data setswithin its information management cell (or another cell) to be searchedin response to certain queries. Such queries may be entered by the userby interacting with user interface 158.

Various embodiments of information management system 100 may beconfigured and/or designed to generate user interface data usable forrendering the various interactive user interfaces described. The userinterface data may be used by system 100 and/or by another system,device, and/or software program (for example, a browser program), torender the interactive user interfaces. The interactive user interfacesmay be displayed on, for example, electronic displays (including, forexample, touch-enabled displays), consoles, etc., whetherdirect-connected to storage manager 140 or communicatively coupledremotely, e.g., via an internet connection. The present disclosuredescribes various embodiments of interactive and dynamic userinterfaces, some of which may be generated by user interface agent 158,and which are the result of significant technological development. Theuser interfaces described herein may provide improved human-computerinteractions, allowing for significant cognitive and ergonomicefficiencies and advantages over previous systems, including reducedmental workloads, improved decision-making, and the like. User interface158 may operate in a single integrated view or console (not shown). Theconsole may support a reporting capability for generating a variety ofreports, which may be tailored to a particular aspect of informationmanagement.

User interfaces are not exclusive to storage manager 140 and in someembodiments a user may access information locally from a computingdevice component of system 100. For example, some information pertainingto installed data agents 142 and associated data streams may beavailable from client computing device 102. Likewise, some informationpertaining to media agents 144 and associated data streams may beavailable from secondary storage computing device 106.

Storage Manager Management Agent

Management agent 154 can provide storage manager 140 with the ability tocommunicate with other components within system 100 and/or with otherinformation management cells via network protocols and applicationprogramming interfaces (APIs) including, e.g., HTTP, HTTPS, FTP, REST,virtualization software APIs, cloud service provider APIs, and hostedservice provider APIs, without limitation. Management agent 154 alsoallows multiple information management cells to communicate with oneanother. For example, system 100 in some cases may be one informationmanagement cell in a network of multiple cells adjacent to one anotheror otherwise logically related, e.g., in a WAN or LAN. With thisarrangement, the cells may communicate with one another throughrespective management agents 154. Inter-cell communications andhierarchy is described in greater detail in e.g., U.S. Pat. No.7,343,453.

Information Management Cell

An “information management cell” (or “storage operation cell” or “cell”)may generally include a logical and/or physical grouping of acombination of hardware and software components associated withperforming information management operations on electronic data,typically one storage manager 140 and at least one data agent 142(executing on a client computing device 102) and at least one mediaagent 144 (executing on a secondary storage computing device 106). Forinstance, the components shown in FIG. 1C may together form aninformation management cell. Thus, in some configurations, a system 100may be referred to as an information management cell or a storageoperation cell. A given cell may be identified by the identity of itsstorage manager 140, which is generally responsible for managing thecell.

Multiple cells may be organized hierarchically, so that cells mayinherit properties from hierarchically superior cells or be controlledby other cells in the hierarchy (automatically or otherwise).Alternatively, in some embodiments, cells may inherit or otherwise beassociated with information management policies, preferences,information management operational parameters, or other properties orcharacteristics according to their relative position in a hierarchy ofcells. Cells may also be organized hierarchically according to function,geography, architectural considerations, or other factors useful ordesirable in performing information management operations. For example,a first cell may represent a geographic segment of an enterprise, suchas a Chicago office, and a second cell may represent a differentgeographic segment, such as a New York City office. Other cells mayrepresent departments within a particular office, e.g., human resources,finance, engineering, etc. Where delineated by function, a first cellmay perform one or more first types of information management operations(e.g., one or more first types of secondary copies at a certainfrequency), and a second cell may perform one or more second types ofinformation management operations (e.g., one or more second types ofsecondary copies at a different frequency and under different retentionrules). In general, the hierarchical information is maintained by one ormore storage managers 140 that manage the respective cells (e.g., incorresponding management database(s) 146).

Data Agents

A variety of different applications 110 can operate on a given clientcomputing device 102, including operating systems, file systems,database applications, e-mail applications, and virtual machines, justto name a few. And, as part of the process of creating and restoringsecondary copies 116, the client computing device 102 may be tasked withprocessing and preparing the primary data 112 generated by these variousapplications 110. Moreover, the nature of the processing/preparation candiffer across application types, e.g., due to inherent structural,state, and formatting differences among applications 110 and/or theoperating system of client computing device 102. Each data agent 142 istherefore advantageously configured in some embodiments to assist in theperformance of information management operations based on the type ofdata that is being protected at a client-specific and/orapplication-specific level.

Data agent 142 is a component of information system 100 and is generallydirected by storage manager 140 to participate in creating or restoringsecondary copies 116. Data agent 142 may be a software program (e.g., inthe form of a set of executable binary files) that executes on the sameclient computing device 102 as the associated application 110 that dataagent 142 is configured to protect. Data agent 142 is generallyresponsible for managing, initiating, or otherwise assisting in theperformance of information management operations in reference to itsassociated application(s) 110 and corresponding primary data 112 whichis generated/accessed by the particular application(s) 110. Forinstance, data agent 142 may take part in copying, archiving, migrating,and/or replicating of certain primary data 112 stored in the primarystorage device(s) 104. Data agent 142 may receive control informationfrom storage manager 140, such as commands to transfer copies of dataobjects and/or metadata to one or more media agents 144. Data agent 142also may compress, deduplicate, and encrypt certain primary data 112, aswell as capture application-related metadata before transmitting theprocessed data to media agent 144. Data agent 142 also may receiveinstructions from storage manager 140 to restore (or assist inrestoring) a secondary copy 116 from secondary storage device 108 toprimary storage 104, such that the restored data may be properlyaccessed by application 110 in a suitable format as though it wereprimary data 112.

Each data agent 142 may be specialized for a particular application 110.For instance, different individual data agents 142 may be designed tohandle Microsoft Exchange data, Lotus Notes data, Microsoft Windows filesystem data, Microsoft Active Directory Objects data, SQL Server data,SharePoint data, Oracle database data, SAP database data, virtualmachines and/or associated data, and other types of data. A file systemdata agent, for example, may handle data files and/or other file systeminformation. If a client computing device 102 has two or more types ofdata 112, a specialized data agent 142 may be used for each data type.For example, to backup, migrate, and/or restore all of the data on aMicrosoft Exchange server, the client computing device 102 may use: (1)a Microsoft Exchange Mailbox data agent 142 to back up the Exchangemailboxes; (2) a Microsoft Exchange Database data agent 142 to back upthe Exchange databases; (3) a Microsoft Exchange Public Folder dataagent 142 to back up the Exchange Public Folders; and (4) a MicrosoftWindows File System data agent 142 to back up the file system of clientcomputing device 102. In this example, these specialized data agents 142are treated as four separate data agents 142 even though they operate onthe same client computing device 102. Other examples may include archivemanagement data agents such as a migration archiver or a compliancearchiver, Quick Recovery® agents, and continuous data replicationagents. Application-specific data agents 142 can provide improvedperformance as compared to generic agents. For instance, becauseapplication-specific data agents 142 may only handle data for a singlesoftware application, the design, operation, and performance of the dataagent 142 can be streamlined. The data agent 142 may therefore executefaster and consume less persistent storage and/or operating memory thandata agents designed to generically accommodate multiple differentsoftware applications 110.

Each data agent 142 may be configured to access data and/or metadatastored in the primary storage device(s) 104 associated with data agent142 and its host client computing device 102, and process the dataappropriately. For example, during a secondary copy operation, dataagent 142 may arrange or assemble the data and metadata into one or morefiles having a certain format (e.g., a particular backup or archiveformat) before transferring the file(s) to a media agent 144 or othercomponent. The file(s) may include a list of files or other metadata. Insome embodiments, a data agent 142 may be distributed between clientcomputing device 102 and storage manager 140 (and any other intermediatecomponents) or may be deployed from a remote location or its functionsapproximated by a remote process that performs some or all of thefunctions of data agent 142. In addition, a data agent 142 may performsome functions provided by media agent 144. Other embodiments may employone or more generic data agents 142 that can handle and process datafrom two or more different applications 110, or that can handle andprocess multiple data types, instead of or in addition to usingspecialized data agents 142. For example, one generic data agent 142 maybe used to back up, migrate and restore Microsoft Exchange Mailbox dataand Microsoft Exchange Database data, while another generic data agentmay handle Microsoft Exchange Public Folder data and Microsoft WindowsFile System data.

Media Agents

As noted, off-loading certain responsibilities from client computingdevices 102 to intermediate components such as secondary storagecomputing device(s) 106 and corresponding media agent(s) 144 can providea number of benefits including improved performance of client computingdevice 102, faster and more reliable information management operations,and enhanced scalability. In one example which will be discussed furtherbelow, media agent 144 can act as a local cache of recently-copied dataand/or metadata stored to secondary storage device(s) 108, thusimproving restore capabilities and performance for the cached data.

Media agent 144 is a component of system 100 and is generally directedby storage manager 140 in creating and restoring secondary copies 116.Whereas storage manager 140 generally manages system 100 as a whole,media agent 144 provides a portal to certain secondary storage devices108, such as by having specialized features for communicating with andaccessing certain associated secondary storage device 108. Media agent144 may be a software program (e.g., in the form of a set of executablebinary files) that executes on a secondary storage computing device 106.Media agent 144 generally manages, coordinates, and facilitates thetransmission of data between a data agent 142 (executing on clientcomputing device 102) and secondary storage device(s) 108 associatedwith media agent 144. For instance, other components in the system mayinteract with media agent 144 to gain access to data stored onassociated secondary storage device(s) 108, (e.g., to browse, read,write, modify, delete, or restore data). Moreover, media agents 144 cangenerate and store information relating to characteristics of the storeddata and/or metadata, or can generate and store other types ofinformation that generally provides insight into the contents of thesecondary storage devices 108—generally referred to as indexing of thestored secondary copies 116. Each media agent 144 may operate on adedicated secondary storage computing device 106, while in otherembodiments a plurality of media agents 144 may operate on the samesecondary storage computing device 106.

A media agent 144 may be associated with a particular secondary storagedevice 108 if that media agent 144 is capable of one or more of: routingand/or storing data to the particular secondary storage device 108;coordinating the routing and/or storing of data to the particularsecondary storage device 108; retrieving data from the particularsecondary storage device 108; coordinating the retrieval of data fromthe particular secondary storage device 108; and modifying and/ordeleting data retrieved from the particular secondary storage device108. Media agent 144 in certain embodiments is physically separate fromthe associated secondary storage device 108. For instance, a media agent144 may operate on a secondary storage computing device 106 in adistinct housing, package, and/or location from the associated secondarystorage device 108. In one example, a media agent 144 operates on afirst server computer and is in communication with a secondary storagedevice(s) 108 operating in a separate rack-mounted RAID-based system.

A media agent 144 associated with a particular secondary storage device108 may instruct secondary storage device 108 to perform an informationmanagement task. For instance, a media agent 144 may instruct a tapelibrary to use a robotic arm or other retrieval means to load or eject acertain storage media, and to subsequently archive, migrate, or retrievedata to or from that media, e.g., for the purpose of restoring data to aclient computing device 102. As another example, a secondary storagedevice 108 may include an array of hard disk drives or solid statedrives organized in a RAID configuration, and media agent 144 mayforward a logical unit number (LUN) and other appropriate information tothe array, which uses the received information to execute the desiredsecondary copy operation. Media agent 144 may communicate with asecondary storage device 108 via a suitable communications link, such asa SCSI or Fibre Channel link.

Each media agent 144 may maintain an associated media agent database152. Media agent database 152 may be stored to a disk or other storagedevice (not shown) that is local to the secondary storage computingdevice 106 on which media agent 144 executes. In other cases, mediaagent database 152 is stored separately from the host secondary storagecomputing device 106. Media agent database 152 can include, among otherthings, a media agent index 153 (see, e.g., FIG. 1C). In some cases,media agent index 153 does not form a part of and is instead separatefrom media agent database 152.

Media agent index 153 (or “index 153”) may be a data structureassociated with the particular media agent 144 that includes informationabout the stored data associated with the particular media agent andwhich may be generated in the course of performing a secondary copyoperation or a restore. Index 153 provides a fast and efficientmechanism for locating/browsing secondary copies 116 or other datastored in secondary storage devices 108 without having to accesssecondary storage device 108 to retrieve the information from there. Forinstance, for each secondary copy 116, index 153 may include metadatasuch as a list of the data objects (e.g., files/subdirectories, databaseobjects, mailbox objects, etc.), a logical path to the secondary copy116 on the corresponding secondary storage device 108, locationinformation (e.g., offsets) indicating where the data objects are storedin the secondary storage device 108, when the data objects were createdor modified, etc. Thus, index 153 includes metadata associated with thesecondary copies 116 that is readily available for use from media agent144. In some embodiments, some or all of the information in index 153may instead or additionally be stored along with secondary copies 116 insecondary storage device 108. In some embodiments, a secondary storagedevice 108 can include sufficient information to enable a “bare metalrestore,” where the operating system and/or software applications of afailed client computing device 102 or another target may beautomatically restored without manually reinstalling individual softwarepackages (including operating systems).

Because index 153 may operate as a cache, it can also be referred to asan “index cache.” In such cases, information stored in index cache 153typically comprises data that reflects certain particulars aboutrelatively recent secondary copy operations. After some triggeringevent, such as after some time elapses or index cache 153 reaches aparticular size, certain portions of index cache 153 may be copied ormigrated to secondary storage device 108, e.g., on a least-recently-usedbasis. This information may be retrieved and uploaded back into indexcache 153 or otherwise restored to media agent 144 to facilitateretrieval of data from the secondary storage device(s) 108. In someembodiments, the cached information may include format orcontainerization information related to archives or other files storedon storage device(s) 108.

In some alternative embodiments media agent 144 generally acts as acoordinator or facilitator of secondary copy operations between clientcomputing devices 102 and secondary storage devices 108, but does notactually write the data to secondary storage device 108. For instance,storage manager 140 (or media agent 144) may instruct a client computingdevice 102 and secondary storage device 108 to communicate with oneanother directly. In such a case, client computing device 102 transmitsdata directly or via one or more intermediary components to secondarystorage device 108 according to the received instructions, and viceversa. Media agent 144 may still receive, process, and/or maintainmetadata related to the secondary copy operations, i.e., may continue tobuild and maintain index 153. In these embodiments, payload data canflow through media agent 144 for the purposes of populating index 153,but not for writing to secondary storage device 108. Media agent 144and/or other components such as storage manager 140 may in some casesincorporate additional functionality, such as data classification,content indexing, deduplication, encryption, compression, and the like.Further details regarding these and other functions are described below.

Distributed, Scalable Architecture

As described, certain functions of system 100 can be distributed amongstvarious physical and/or logical components. For instance, one or more ofstorage manager 140, data agents 142, and media agents 144 may operateon computing devices that are physically separate from one another. Thisarchitecture can provide a number of benefits. For instance, hardwareand software design choices for each distributed component can betargeted to suit its particular function. The secondary computingdevices 106 on which media agents 144 operate can be tailored forinteraction with associated secondary storage devices 108 and providefast index cache operation, among other specific tasks. Similarly,client computing device(s) 102 can be selected to effectively serviceapplications 110 in order to efficiently produce and store primary data112.

Moreover, in some cases, one or more of the individual components ofinformation management system 100 can be distributed to multipleseparate computing devices. As one example, for large file systems wherethe amount of data stored in management database 146 is relativelylarge, database 146 may be migrated to or may otherwise reside on aspecialized database server (e.g., an SQL server) separate from a serverthat implements the other functions of storage manager 140. Thisdistributed configuration can provide added protection because database146 can be protected with standard database utilities (e.g., SQL logshipping or database replication) independent from other functions ofstorage manager 140. Database 146 can be efficiently replicated to aremote site for use in the event of a disaster or other data loss at theprimary site. Or database 146 can be replicated to another computingdevice within the same site, such as to a higher performance machine inthe event that a storage manager host computing device can no longerservice the needs of a growing system 100.

The distributed architecture also provides scalability and efficientcomponent utilization. FIG. 1D shows an embodiment of informationmanagement system 100 including a plurality of client computing devices102 and associated data agents 142 as well as a plurality of secondarystorage computing devices 106 and associated media agents 144.Additional components can be added or subtracted based on the evolvingneeds of system 100. For instance, depending on where bottlenecks areidentified, administrators can add additional client computing devices102, secondary storage computing devices 106, and/or secondary storagedevices 108. Moreover, where multiple fungible components are available,load balancing can be implemented to dynamically address identifiedbottlenecks. As an example, storage manager 140 may dynamically selectwhich media agents 144 and/or secondary storage devices 108 to use forstorage operations based on a processing load analysis of media agents144 and/or secondary storage devices 108, respectively.

Where system 100 includes multiple media agents 144 (see, e.g., FIG.1D), a first media agent 144 may provide failover functionality for asecond failed media agent 144. In addition, media agents 144 can bedynamically selected to provide load balancing. Each client computingdevice 102 can communicate with, among other components, any of themedia agents 144, e.g., as directed by storage manager 140. And eachmedia agent 144 may communicate with, among other components, any ofsecondary storage devices 108, e.g., as directed by storage manager 140.Thus, operations can be routed to secondary storage devices 108 in adynamic and highly flexible manner, to provide load balancing, failover,etc. Further examples of scalable systems capable of dynamic storageoperations, load balancing, and failover are provided in U.S. Pat. No.7,246,207.

While distributing functionality amongst multiple computing devices canhave certain advantages, in other contexts it can be beneficial toconsolidate functionality on the same computing device. In alternativeconfigurations, certain components may reside and execute on the samecomputing device. As such, in other embodiments, one or more of thecomponents shown in FIG. 1C may be implemented on the same computingdevice. In one configuration, a storage manager 140, one or more dataagents 142, and/or one or more media agents 144 are all implemented onthe same computing device. In other embodiments, one or more data agents142 and one or more media agents 144 are implemented on the samecomputing device, while storage manager 140 is implemented on a separatecomputing device, etc. without limitation.

Exemplary Types of Information Management Operations, Including StorageOperations

In order to protect and leverage stored data, system 100 can beconfigured to perform a variety of information management operations,which may also be referred to in some cases as storage managementoperations or storage operations. These operations can generally include(i) data movement operations, (ii) processing and data manipulationoperations, and (iii) analysis, reporting, and management operations.

Data Movement Operations, Including Secondary Copy Operations

Data movement operations are generally storage operations that involvethe copying or migration of data between different locations in system100. For example, data movement operations can include operations inwhich stored data is copied, migrated, or otherwise transferred from oneor more first storage devices to one or more second storage devices,such as from primary storage device(s) 104 to secondary storagedevice(s) 108, from secondary storage device(s) 108 to differentsecondary storage device(s) 108, from secondary storage devices 108 toprimary storage devices 104, or from primary storage device(s) 104 todifferent primary storage device(s) 104, or in some cases within thesame primary storage device 104 such as within a storage array.

Data movement operations can include by way of example, backupoperations, archive operations, information lifecycle managementoperations such as hierarchical storage management operations,replication operations (e.g., continuous data replication), snapshotoperations, deduplication or single-instancing operations, auxiliarycopy operations, disaster-recovery copy operations, and the like. Aswill be discussed, some of these operations do not necessarily createdistinct copies. Nonetheless, some or all of these operations aregenerally referred to as “secondary copy operations” for simplicity,because they involve secondary copies. Data movement also comprisesrestoring secondary copies.

Backup Operations

A backup operation creates a copy of a version of primary data 112 at aparticular point in time (e.g., one or more files or other data units).Each subsequent backup copy 116 (which is a form of secondary copy 116)may be maintained independently of the first. A backup generallyinvolves maintaining a version of the copied primary data 112 as well asbackup copies 116. Further, a backup copy in some embodiments isgenerally stored in a form that is different from the native format,e.g., a backup format. This contrasts to the version in primary data 112which may instead be stored in a format native to the sourceapplication(s) 110. In various cases, backup copies can be stored in aformat in which the data is compressed, encrypted, deduplicated, and/orotherwise modified from the original native application format. Forexample, a backup copy may be stored in a compressed backup format thatfacilitates efficient long-term storage. Backup copies 116 can haverelatively long retention periods as compared to primary data 112, whichis generally highly changeable. Backup copies 116 may be stored on mediawith slower retrieval times than primary storage device 104. Some backupcopies may have shorter retention periods than some other types ofsecondary copies 116, such as archive copies (described below). Backupsmay be stored at an offsite location.

Backup operations can include full backups, differential backups,incremental backups, “synthetic full” backups, and/or creating a“reference copy.” A full backup (or “standard full backup”) in someembodiments is generally a complete image of the data to be protected.However, because full backup copies can consume a relatively largeamount of storage, it can be useful to use a full backup copy as abaseline and only store changes relative to the full backup copyafterwards.

A differential backup operation (or cumulative incremental backupoperation) tracks and stores changes that occurred since the last fullbackup. Differential backups can grow quickly in size, but can restorerelatively efficiently because a restore can be completed in some casesusing only the full backup copy and the latest differential copy.

An incremental backup operation generally tracks and stores changessince the most recent backup copy of any type, which can greatly reducestorage utilization. In some cases, however, restoring can be lengthycompared to full or differential backups because completing a restoreoperation may involve accessing a full backup in addition to multipleincremental backups.

Synthetic full backups generally consolidate data without directlybacking up data from the client computing device. A synthetic fullbackup is created from the most recent full backup (i.e., standard orsynthetic) and subsequent incremental and/or differential backups. Theresulting synthetic full backup is identical to what would have beencreated had the last backup for the subclient been a standard fullbackup. Unlike standard full, incremental, and differential backups,however, a synthetic full backup does not actually transfer data fromprimary storage to the backup media, because it operates as a backupconsolidator. A synthetic full backup extracts the index data of eachparticipating subclient. Using this index data and the previously backedup user data images, it builds new full backup images (e.g., bitmaps),one for each subclient. The new backup images consolidate the index anduser data stored in the related incremental, differential, and previousfull backups into a synthetic backup file that fully represents thesubclient (e.g., via pointers) but does not comprise all its constituentdata.

Any of the above types of backup operations can be at the volume level,file level, or block level. Volume level backup operations generallyinvolve copying of a data volume (e.g., a logical disk or partition) asa whole. In a file-level backup, information management system 100generally tracks changes to individual files and includes copies offiles in the backup copy. For block-level backups, files are broken intoconstituent blocks, and changes are tracked at the block level. Uponrestore, system 100 reassembles the blocks into files in a transparentfashion. Far less data may actually be transferred and copied tosecondary storage devices 108 during a file-level copy than avolume-level copy. Likewise, a block-level copy may transfer less datathan a file-level copy, resulting in faster execution. However,restoring a relatively higher-granularity copy can result in longerrestore times. For instance, when restoring a block-level copy, theprocess of locating and retrieving constituent blocks can sometimes takelonger than restoring file-level backups.

A reference copy may comprise copy(ies) of selected objects from backedup data, typically to help organize data by keeping contextualinformation from multiple sources together, and/or help retain specificdata for a longer period of time, such as for legal hold needs. Areference copy generally maintains data integrity, and when the data isrestored, it may be viewed in the same format as the source data. Insome embodiments, a reference copy is based on a specialized client,individual subclient and associated information management policies(e.g., storage policy, retention policy, etc.) that are administeredwithin system 100.

Archive Operations

Because backup operations generally involve maintaining a version of thecopied primary data 112 and also maintaining backup copies in secondarystorage device(s) 108, they can consume significant storage capacity. Toreduce storage consumption, an archive operation according to certainembodiments creates an archive copy 116 by both copying and removingsource data. Or, seen another way, archive operations can involve movingsome or all of the source data to the archive destination. Thus, datasatisfying criteria for removal (e.g., data of a threshold age or size)may be removed from source storage. The source data may be primary data112 or a secondary copy 116, depending on the situation. As with backupcopies, archive copies can be stored in a format in which the data iscompressed, encrypted, deduplicated, and/or otherwise modified from theformat of the original application or source copy. In addition, archivecopies may be retained for relatively long periods of time (e.g., years)and, in some cases are never deleted. In certain embodiments, archivecopies may be made and kept for extended periods in order to meetcompliance regulations.

Archiving can also serve the purpose of freeing up space in primarystorage device(s) 104 and easing the demand on computational resourceson client computing device 102. Similarly, when a secondary copy 116 isarchived, the archive copy can therefore serve the purpose of freeing upspace in the source secondary storage device(s) 108. Examples of dataarchiving operations are provided in U.S. Pat. No. 7,107,298.

Snapshot Operations

Snapshot operations can provide a relatively lightweight, efficientmechanism for protecting data. From an end-user viewpoint, a snapshotmay be thought of as an “instant” image of primary data 112 at a givenpoint in time, and may include state and/or status information relativeto an application 110 that creates/manages primary data 112. In oneembodiment, a snapshot may generally capture the directory structure ofan object in primary data 112 such as a file or volume or other data setat a particular moment in time and may also preserve file attributes andcontents. A snapshot in some cases is created relatively quickly, e.g.,substantially instantly, using a minimum amount of file space, but maystill function as a conventional file system backup.

A “hardware snapshot” (or “hardware-based snapshot”) operation occurswhere a target storage device (e.g., a primary storage device 104 or asecondary storage device 108) performs the snapshot operation in aself-contained fashion, substantially independently, using hardware,firmware and/or software operating on the storage device itself. Forinstance, the storage device may perform snapshot operations generallywithout intervention or oversight from any of the other components ofthe system 100, e.g., a storage array may generate an “array-created”hardware snapshot and may also manage its storage, integrity,versioning, etc. In this manner, hardware snapshots can off-load othercomponents of system 100 from snapshot processing. An array may receivea request from another component to take a snapshot and then proceed toexecute the “hardware snapshot” operations autonomously, preferablyreporting success to the requesting component.

A “software snapshot” (or “software-based snapshot”) operation, on theother hand, occurs where a component in system 100 (e.g., clientcomputing device 102, etc.) implements a software layer that manages thesnapshot operation via interaction with the target storage device. Forinstance, the component executing the snapshot management software layermay derive a set of pointers and/or data that represents the snapshot.The snapshot management software layer may then transmit the same to thetarget storage device, along with appropriate instructions for writingthe snapshot. One example of a software snapshot product is MicrosoftVolume Snapshot Service (VSS), which is part of the Microsoft Windowsoperating system.

Some types of snapshots do not actually create another physical copy ofall the data as it existed at the particular point in time, but maysimply create pointers that map files and directories to specific memorylocations (e.g., to specific disk blocks) where the data resides as itexisted at the particular point in time. For example, a snapshot copymay include a set of pointers derived from the file system or from anapplication. In some other cases, the snapshot may be created at theblock-level, such that creation of the snapshot occurs without awarenessof the file system. Each pointer points to a respective stored datablock, so that collectively, the set of pointers reflect the storagelocation and state of the data object (e.g., file(s) or volume(s) ordata set(s)) at the point in time when the snapshot copy was created.

An initial snapshot may use only a small amount of disk space needed torecord a mapping or other data structure representing or otherwisetracking the blocks that correspond to the current state of the filesystem. Additional disk space is usually required only when files anddirectories change later on. Furthermore, when files change, typicallyonly the pointers which map to blocks are copied, not the blocksthemselves. For example for “copy-on-write” snapshots, when a blockchanges in primary storage, the block is copied to secondary storage orcached in primary storage before the block is overwritten in primarystorage, and the pointer to that block is changed to reflect the newlocation of that block. The snapshot mapping of file system data mayalso be updated to reflect the changed block(s) at that particular pointin time. In some other cases, a snapshot includes a full physical copyof all or substantially all of the data represented by the snapshot.Further examples of snapshot operations are provided in U.S. Pat. No.7,529,782. A snapshot copy in many cases can be made quickly and withoutsignificantly impacting primary computing resources because largeamounts of data need not be copied or moved. In some embodiments, asnapshot may exist as a virtual file system, parallel to the actual filesystem. Users in some cases gain read-only access to the record of filesand directories of the snapshot. By electing to restore primary data 112from a snapshot taken at a given point in time, users may also returnthe current file system to the state of the file system that existedwhen the snapshot was taken.

Replication Operations

Replication is another type of secondary copy operation. Some types ofsecondary copies 116 periodically capture images of primary data 112 atparticular points in time (e.g., backups, archives, and snapshots).However, it can also be useful for recovery purposes to protect primarydata 112 in a more continuous fashion, by replicating primary data 112substantially as changes occur. In some cases a replication copy can bea mirror copy, for instance, where changes made to primary data 112 aremirrored or substantially immediately copied to another location (e.g.,to secondary storage device(s) 108). By copying each write operation tothe replication copy, two storage systems are kept synchronized orsubstantially synchronized so that they are virtually identical atapproximately the same time. Where entire disk volumes are mirrored,however, mirroring can require significant amount of storage space andutilizes a large amount of processing resources.

According to some embodiments, secondary copy operations are performedon replicated data that represents a recoverable state, or “known goodstate” of a particular application running on the source system. Forinstance, in certain embodiments, known good replication copies may beviewed as copies of primary data 112. This feature allows the system todirectly access, copy, restore, back up, or otherwise manipulate thereplication copies as if they were the “live” primary data 112. This canreduce access time, storage utilization, and impact on sourceapplications 110, among other benefits. Based on known good stateinformation, system 100 can replicate sections of application data thatrepresent a recoverable state rather than rote copying of blocks ofdata. Examples of replication operations (e.g., continuous datareplication) are provided in U.S. Pat. No. 7,617,262.

Deduplication/Single-Instancing Operations

Deduplication or single-instance storage is useful to reduce the amountof non-primary data. For instance, some or all of the above-describedsecondary copy operations can involve deduplication in some fashion. Newdata is read, broken down into data portions of a selected granularity(e.g., sub-file level blocks, files, etc.), compared with correspondingportions that are already in secondary storage, and only new/changedportions are stored. Portions that already exist are represented aspointers to the already-stored data. Thus, a deduplicated secondary copy116 may comprise actual data portions copied from primary data 112 andmay further comprise pointers to already-stored data, which is generallymore storage-efficient than a full copy.

In order to streamline the comparison process, system 100 may calculateand/or store signatures (e.g., hashes or cryptographically unique IDs)corresponding to the individual source data portions and compare thesignatures to already-stored data signatures, instead of comparingentire data portions. In some cases, only a single instance of each dataportion is stored, and deduplication operations may therefore bereferred to interchangeably as “single-instancing” operations. Dependingon the implementation, however, deduplication operations can store morethan one instance of certain data portions, yet still significantlyreduce stored-data redundancy. Depending on the embodiment,deduplication portions such as data blocks can be of fixed or variablelength. Using variable length blocks can enhance deduplication byresponding to changes in the data stream, but can involve more complexprocessing. In some cases, system 100 utilizes a technique fordynamically aligning deduplication blocks based on changing content inthe data stream, as described in U.S. Pat. No. 8,364,652.

System 100 can deduplicate in a variety of manners at a variety oflocations. For instance, in some embodiments, system 100 implements“target-side” deduplication by deduplicating data at the media agent 144after being received from data agent 142. In some such cases, mediaagents 144 are generally configured to manage the deduplication process.For instance, one or more of the media agents 144 maintain acorresponding deduplication database that stores deduplicationinformation (e.g., data block signatures). Examples of such aconfiguration are provided in U.S. Pat. No. 9,020,900. Instead of or incombination with “target-side” deduplication, “source-side” (or“client-side”) deduplication can also be performed, e.g., to reduce theamount of data to be transmitted by data agent 142 to media agent 144.Storage manager 140 may communicate with other components within system100 via network protocols and cloud service provider APIs to facilitatecloud-based deduplication/single instancing, as exemplified in U.S. Pat.No. 8,954,446. Some other deduplication/single instancing techniques aredescribed in U.S. Pat. Pub. No. 2006/0224846 and in U.S. Pat. No.9,098,495.

Information Lifecycle Management and Hierarchical Storage Management

In some embodiments, files and other data over their lifetime move frommore expensive quick-access storage to less expensive slower-accessstorage. Operations associated with moving data through various tiers ofstorage are sometimes referred to as information lifecycle management(ILM) operations.

One type of ILM operation is a hierarchical storage management (HSM)operation, which generally automatically moves data between classes ofstorage devices, such as from high-cost to low-cost storage devices. Forinstance, an HSM operation may involve movement of data from primarystorage devices 104 to secondary storage devices 108, or between tiersof secondary storage devices 108. With each tier, the storage devicesmay be progressively cheaper, have relatively slower access/restoretimes, etc. For example, movement of data between tiers may occur asdata becomes less important over time. In some embodiments, an HSMoperation is similar to archiving in that creating an HSM copy may(though not always) involve deleting some of the source data, e.g.,according to one or more criteria related to the source data. Forexample, an HSM copy may include primary data 112 or a secondary copy116 that exceeds a given size threshold or a given age threshold. Often,and unlike some types of archive copies, HSM data that is removed oraged from the source is replaced by a logical reference pointer or stub.The reference pointer or stub can be stored in the primary storagedevice 104 or other source storage device, such as a secondary storagedevice 108 to replace the deleted source data and to point to orotherwise indicate the new location in (another) secondary storagedevice 108.

For example, files are generally moved between higher and lower coststorage depending on how often the files are accessed. When a userrequests access to HSM data that has been removed or migrated, system100 uses the stub to locate the data and can make recovery of the dataappear transparent, even though the HSM data may be stored at a locationdifferent from other source data. In this manner, the data appears tothe user (e.g., in file system browsing windows and the like) as if itstill resides in the source location (e.g., in a primary storage device104). The stub may include metadata associated with the correspondingdata, so that a file system and/or application can provide someinformation about the data object and/or a limited-functionality version(e.g., a preview) of the data object.

An HSM copy may be stored in a format other than the native applicationformat (e.g., compressed, encrypted, deduplicated, and/or otherwisemodified). In some cases, copies which involve the removal of data fromsource storage and the maintenance of stub or other logical referenceinformation on source storage may be referred to generally as “onlinearchive copies.” On the other hand, copies which involve the removal ofdata from source storage without the maintenance of stub or otherlogical reference information on source storage may be referred to as“off-line archive copies.” Examples of HSM and ILM techniques areprovided in U.S. Pat. No. 7,343,453.

Auxiliary Copy Operations

An auxiliary copy is generally a copy of an existing secondary copy 116.For instance, an initial secondary copy 116 may be derived from primarydata 112 or from data residing in secondary storage subsystem 118,whereas an auxiliary copy is generated from the initial secondary copy116. Auxiliary copies provide additional standby copies of data and mayreside on different secondary storage devices 108 than the initialsecondary copies 116. Thus, auxiliary copies can be used for recoverypurposes if initial secondary copies 116 become unavailable. Exemplaryauxiliary copy techniques are described in further detail in U.S. Pat.No. 8,230,195.

Disaster-Recovery Copy Operations

System 100 may also make and retain disaster recovery copies, often assecondary, high-availability disk copies. System 100 may createsecondary copies and store them at disaster recovery locations usingauxiliary copy or replication operations, such as continuous datareplication technologies. Depending on the particular data protectiongoals, disaster recovery locations can be remote from the clientcomputing devices 102 and primary storage devices 104, remote from someor all of the secondary storage devices 108, or both.

Data Manipulation, Including Encryption and Compression

Data manipulation and processing may include encryption and compressionas well as integrity marking and checking, formatting for transmission,formatting for storage, etc. Data may be manipulated “client-side” bydata agent 142 as well as “target-side” by media agent 144 in the courseof creating secondary copy 116, or conversely in the course of restoringdata from secondary to primary.

Encryption Operations

System 100 in some cases is configured to process data (e.g., files orother data objects, primary data 112, secondary copies 116, etc.),according to an appropriate encryption algorithm (e.g., Blowfish,Advanced Encryption Standard (AES), Triple Data Encryption Standard(3-DES), etc.) to limit access and provide data security. System 100 insome cases encrypts the data at the client level, such that clientcomputing devices 102 (e.g., data agents 142) encrypt the data prior totransferring it to other components, e.g., before sending the data tomedia agents 144 during a secondary copy operation. In such cases,client computing device 102 may maintain or have access to an encryptionkey or passphrase for decrypting the data upon restore. Encryption canalso occur when media agent 144 creates auxiliary copies or archivecopies. Encryption may be applied in creating a secondary copy 116 of apreviously unencrypted secondary copy 116, without limitation. Infurther embodiments, secondary storage devices 108 can implementbuilt-in, high performance hardware-based encryption.

Compression Operations

Similar to encryption, system 100 may also or alternatively compressdata in the course of generating a secondary copy 116. Compressionencodes information such that fewer bits are needed to represent theinformation as compared to the original representation. Compressiontechniques are well known in the art. Compression operations may applyone or more data compression algorithms. Compression may be applied increating a secondary copy 116 of a previously uncompressed secondarycopy, e.g., when making archive copies or disaster recovery copies. Theuse of compression may result in metadata that specifies the nature ofthe compression, so that data may be uncompressed on restore ifappropriate.

Data Analysis, Reporting, and Management Operations

Data analysis, reporting, and management operations can differ from datamovement operations in that they do not necessarily involve copying,migration or other transfer of data between different locations in thesystem. For instance, data analysis operations may involve processing(e.g., offline processing) or modification of already stored primarydata 112 and/or secondary copies 116. However, in some embodiments dataanalysis operations are performed in conjunction with data movementoperations. Some data analysis operations include content indexingoperations and classification operations which can be useful inleveraging data under management to enhance search and other features.

Classification Operations/Content Indexing

In some embodiments, information management system 100 analyzes andindexes characteristics, content, and metadata associated with primarydata 112 (“online content indexing”) and/or secondary copies 116(“off-line content indexing”). Content indexing can identify files orother data objects based on content (e.g., user-defined keywords orphrases, other keywords/phrases that are not defined by a user, etc.),and/or metadata (e.g., email metadata such as “to,” “from,” “cc,” “bcc,”attachment name, received time, etc.). Content indexes may be searchedand search results may be restored.

System 100 generally organizes and catalogues the results into a contentindex, which may be stored within media agent database 152, for example.The content index can also include the storage locations of or pointerreferences to indexed data in primary data 112 and/or secondary copies116. Results may also be stored elsewhere in system 100 (e.g., inprimary storage device 104 or in secondary storage device 108). Suchcontent index data provides storage manager 140 or other components withan efficient mechanism for locating primary data 112 and/or secondarycopies 116 of data objects that match particular criteria, thus greatlyincreasing the search speed capability of system 100. For instance,search criteria can be specified by a user through user interface 158 ofstorage manager 140. Moreover, when system 100 analyzes data and/ormetadata in secondary copies 116 to create an “off-line content index,”this operation has no significant impact on the performance of clientcomputing devices 102 and thus does not take a toll on the productionenvironment. Examples of content indexing techniques are provided inU.S. Pat. No. 8,170,995.

One or more components, such as a content index engine, can beconfigured to scan data and/or associated metadata for classificationpurposes to populate a database (or other data structure) ofinformation, which can be referred to as a “data classificationdatabase” or a “metabase.” Depending on the embodiment, the dataclassification database(s) can be organized in a variety of differentways, including centralization, logical sub-divisions, and/or physicalsub-divisions. For instance, one or more data classification databasesmay be associated with different subsystems or tiers within system 100.As an example, there may be a first metabase associated with primarystorage subsystem 117 and a second metabase associated with secondarystorage subsystem 118. In other cases, metabase(s) may be associatedwith individual components, e.g., client computing devices 102 and/ormedia agents 144. In some embodiments, a data classification databasemay reside as one or more data structures within management database146, may be otherwise associated with storage manager 140, and/or mayreside as a separate component. In some cases, metabase(s) may beincluded in separate database(s) and/or on separate storage device(s)from primary data 112 and/or secondary copies 116, such that operationsrelated to the metabase(s) do not significantly impact performance onother components of system 100. In other cases, metabase(s) may bestored along with primary data 112 and/or secondary copies 116. Files orother data objects can be associated with identifiers (e.g., tagentries, etc.) to facilitate searches of stored data objects. Among anumber of other benefits, the metabase can also allow efficient,automatic identification of files or other data objects to associatewith secondary copy or other information management operations. Forinstance, a metabase can dramatically improve the speed with whichsystem 100 can search through and identify data as compared to otherapproaches that involve scanning an entire file system. Examples ofmetabases and data classification operations are provided in U.S. Pat.Nos. 7,734,669 and 7,747,579.

Management and Reporting Operations

Certain embodiments leverage the integrated ubiquitous nature of system100 to provide useful system-wide management and reporting. Operationsmanagement can generally include monitoring and managing the health andperformance of system 100 by, without limitation, performing errortracking, generating granular storage/performance metrics (e.g., jobsuccess/failure information, deduplication efficiency, etc.), generatingstorage modeling and costing information, and the like. As an example,storage manager 140 or another component in system 100 may analyzetraffic patterns and suggest and/or automatically route data to minimizecongestion. In some embodiments, the system can generate predictionsrelating to storage operations or storage operation information. Suchpredictions, which may be based on a trending analysis, may predictvarious network operations or resource usage, such as network trafficlevels, storage media use, use of bandwidth of communication links, useof media agent components, etc. Further examples of traffic analysis,trend analysis, prediction generation, and the like are described inU.S. Pat. No. 7,343,453.

In some configurations having a hierarchy of storage operation cells, amaster storage manager 140 may track the status of subordinate cells,such as the status of jobs, system components, system resources, andother items, by communicating with storage managers 140 (or othercomponents) in the respective storage operation cells. Moreover, themaster storage manager 140 may also track status by receiving periodicstatus updates from the storage managers 140 (or other components) inthe respective cells regarding jobs, system components, systemresources, and other items. In some embodiments, a master storagemanager 140 may store status information and other information regardingits associated storage operation cells and other system information inits management database 146 and/or index 150 (or in another location).The master storage manager 140 or other component may also determinewhether certain storage-related or other criteria are satisfied, and mayperform an action or trigger event (e.g., data migration) in response tothe criteria being satisfied, such as where a storage threshold is metfor a particular volume, or where inadequate protection exists forcertain data. For instance, data from one or more storage operationcells is used to dynamically and automatically mitigate recognizedrisks, and/or to advise users of risks or suggest actions to mitigatethese risks. For example, an information management policy may specifycertain requirements (e.g., that a storage device should maintain acertain amount of free space, that secondary copies should occur at aparticular interval, that data should be aged and migrated to otherstorage after a particular period, that data on a secondary volumeshould always have a certain level of availability and be restorablewithin a given time period, that data on a secondary volume may bemirrored or otherwise migrated to a specified number of other volumes,etc.). If a risk condition or other criterion is triggered, the systemmay notify the user of these conditions and may suggest (orautomatically implement) a mitigation action to address the risk. Forexample, the system may indicate that data from a primary copy 112should be migrated to a secondary storage device 108 to free up space onprimary storage device 104. Examples of the use of risk factors andother triggering criteria are described in U.S. Pat. No. 7,343,453.

In some embodiments, system 100 may also determine whether a metric orother indication satisfies particular storage criteria sufficient toperform an action. For example, a storage policy or other definitionmight indicate that a storage manager 140 should initiate a particularaction if a storage metric or other indication drops below or otherwisefails to satisfy specified criteria such as a threshold of dataprotection. In some embodiments, risk factors may be quantified intocertain measurable service or risk levels. For example, certainapplications and associated data may be considered to be more importantrelative to other data and services. Financial compliance data, forexample, may be of greater importance than marketing materials, etc.Network administrators may assign priority values or “weights” tocertain data and/or applications corresponding to the relativeimportance. The level of compliance of secondary copy operationsspecified for these applications may also be assigned a certain value.Thus, the health, impact, and overall importance of a service may bedetermined, such as by measuring the compliance value and calculatingthe product of the priority value and the compliance value to determinethe “service level” and comparing it to certain operational thresholdsto determine whether it is acceptable. Further examples of the servicelevel determination are provided in U.S. Pat. No. 7,343,453.

System 100 may additionally calculate data costing and data availabilityassociated with information management operation cells. For instance,data received from a cell may be used in conjunction withhardware-related information and other information about system elementsto determine the cost of storage and/or the availability of particulardata. Exemplary information generated could include how fast aparticular department is using up available storage space, how long datawould take to recover over a particular pathway from a particularsecondary storage device, costs over time, etc. Moreover, in someembodiments, such information may be used to determine or predict theoverall cost associated with the storage of certain information. Thecost associated with hosting a certain application may be based, atleast in part, on the type of media on which the data resides, forexample. Storage devices may be assigned to a particular costcategories, for example. Further examples of costing techniques aredescribed in U.S. Pat. No. 7,343,453.

Any of the above types of information (e.g., information related totrending, predictions, job, cell or component status, risk, servicelevel, costing, etc.) can generally be provided to users via userinterface 158 in a single integrated view or console (not shown). Reporttypes may include: scheduling, event management, media management anddata aging. Available reports may also include backup history, dataaging history, auxiliary copy history, job history, library and drive,media in library, restore history, and storage policy, etc., withoutlimitation. Such reports may be specified and created at a certain pointin time as a system analysis, forecasting, or provisioning tool.Integrated reports may also be generated that illustrate storage andperformance metrics, risks and storage costing information. Moreover,users may create their own reports based on specific needs. Userinterface 158 can include an option to graphically depict the variouscomponents in the system using appropriate icons. As one example, userinterface 158 may provide a graphical depiction of primary storagedevices 104, secondary storage devices 108, data agents 142 and/or mediaagents 144, and their relationship to one another in system 100.

In general, the operations management functionality of system 100 canfacilitate planning and decision-making. For example, in someembodiments, a user may view the status of some or all jobs as well asthe status of each component of information management system 100. Usersmay then plan and make decisions based on this data. For instance, auser may view high-level information regarding secondary copy operationsfor system 100, such as job status, component status, resource status(e.g., communication pathways, etc.), and other information. The usermay also drill down or use other means to obtain more detailedinformation regarding a particular component, job, or the like. Furtherexamples are provided in U.S. Pat. No. 7,343,453.

System 100 can also be configured to perform system-wide e-discoveryoperations in some embodiments. In general, e-discovery operationsprovide a unified collection and search capability for data in thesystem, such as data stored in secondary storage devices 108 (e.g.,backups, archives, or other secondary copies 116). For example, system100 may construct and maintain a virtual repository for data stored insystem 100 that is integrated across source applications 110, differentstorage device types, etc. According to some embodiments, e-discoveryutilizes other techniques described herein, such as data classificationand/or content indexing.

Information Management Policies

An information management policy 148 can include a data structure orother information source that specifies a set of parameters (e.g.,criteria and rules) associated with secondary copy and/or otherinformation management operations.

One type of information management policy 148 is a “storage policy.”According to certain embodiments, a storage policy generally comprises adata structure or other information source that defines (or includesinformation sufficient to determine) a set of preferences or othercriteria for performing information management operations. Storagepolicies can include one or more of the following: (1) what data will beassociated with the storage policy, e.g., subclient; (2) a destinationto which the data will be stored; (3) datapath information specifyinghow the data will be communicated to the destination; (4) the type ofsecondary copy operation to be performed; and (5) retention informationspecifying how long the data will be retained at the destination (see,e.g., FIG. 1E). Data associated with a storage policy can be logicallyorganized into subclients, which may represent primary data 112 and/orsecondary copies 116. A subclient may represent static or dynamicassociations of portions of a data volume. Subclients may representmutually exclusive portions. Thus, in certain embodiments, a portion ofdata may be given a label and the association is stored as a staticentity in an index, database or other storage location. Subclients mayalso be used as an effective administrative scheme of organizing dataaccording to data type, department within the enterprise, storagepreferences, or the like. Depending on the configuration, subclients cancorrespond to files, folders, virtual machines, databases, etc. In oneexemplary scenario, an administrator may find it preferable to separatee-mail data from financial data using two different subclients.

A storage policy can define where data is stored by specifying a targetor destination storage device (or group of storage devices). Forinstance, where the secondary storage device 108 includes a group ofdisk libraries, the storage policy may specify a particular disk libraryfor storing the subclients associated with the policy. As anotherexample, where the secondary storage devices 108 include one or moretape libraries, the storage policy may specify a particular tape libraryfor storing the subclients associated with the storage policy, and mayalso specify a drive pool and a tape pool defining a group of tapedrives and a group of tapes, respectively, for use in storing thesubclient data. While information in the storage policy can bestatically assigned in some cases, some or all of the information in thestorage policy can also be dynamically determined based on criteria setforth in the storage policy. For instance, based on such criteria, aparticular destination storage device(s) or other parameter of thestorage policy may be determined based on characteristics associatedwith the data involved in a particular secondary copy operation, deviceavailability (e.g., availability of a secondary storage device 108 or amedia agent 144), network status and conditions (e.g., identifiedbottlenecks), user credentials, and the like.

Datapath information can also be included in the storage policy. Forinstance, the storage policy may specify network pathways and componentsto utilize when moving the data to the destination storage device(s). Insome embodiments, the storage policy specifies one or more media agents144 for conveying data associated with the storage policy between thesource and destination. A storage policy can also specify the type(s) ofassociated operations, such as backup, archive, snapshot, auxiliarycopy, or the like. Furthermore, retention parameters can specify howlong the resulting secondary copies 116 will be kept (e.g., a number ofdays, months, years, etc.), perhaps depending on organizational needsand/or compliance criteria.

When adding a new client computing device 102, administrators canmanually configure information management policies 148 and/or othersettings, e.g., via user interface 158. However, this can be an involvedprocess resulting in delays, and it may be desirable to begin dataprotection operations quickly, without awaiting human intervention.Thus, in some embodiments, system 100 automatically applies a defaultconfiguration to client computing device 102. As one example, when oneor more data agent(s) 142 are installed on a client computing device102, the installation script may register the client computing device102 with storage manager 140, which in turn applies the defaultconfiguration to the new client computing device 102. In this manner,data protection operations can begin substantially immediately. Thedefault configuration can include a default storage policy, for example,and can specify any appropriate information sufficient to begin dataprotection operations. This can include a type of data protectionoperation, scheduling information, a target secondary storage device108, data path information (e.g., a particular media agent 144), and thelike.

Another type of information management policy 148 is a “schedulingpolicy,” which specifies when and how often to perform operations.Scheduling parameters may specify with what frequency (e.g., hourly,weekly, daily, event-based, etc.) or under what triggering conditionssecondary copy or other information management operations are to takeplace. Scheduling policies in some cases are associated with particularcomponents, such as a subclient, client computing device 102, and thelike.

Another type of information management policy 148 is an “audit policy”(or “security policy”), which comprises preferences, rules and/orcriteria that protect sensitive data in system 100. For example, anaudit policy may define “sensitive objects” which are files or dataobjects that contain particular keywords (e.g., “confidential,” or“privileged”) and/or are associated with particular keywords (e.g., inmetadata) or particular flags (e.g., in metadata identifying a documentor email as personal, confidential, etc.). An audit policy may furtherspecify rules for handling sensitive objects. As an example, an auditpolicy may require that a reviewer approve the transfer of any sensitiveobjects to a cloud storage site, and that if approval is denied for aparticular sensitive object, the sensitive object should be transferredto a local primary storage device 104 instead. To facilitate thisapproval, the audit policy may further specify how a secondary storagecomputing device 106 or other system component should notify a reviewerthat a sensitive object is slated for transfer.

Another type of information management policy 148 is a “provisioningpolicy,” which can include preferences, priorities, rules, and/orcriteria that specify how client computing devices 102 (or groupsthereof) may utilize system resources, such as available storage oncloud storage and/or network bandwidth. A provisioning policy specifies,for example, data quotas for particular client computing devices 102(e.g., a number of gigabytes that can be stored monthly, quarterly orannually). Storage manager 140 or other components may enforce theprovisioning policy. For instance, media agents 144 may enforce thepolicy when transferring data to secondary storage devices 108. If aclient computing device 102 exceeds a quota, a budget for the clientcomputing device 102 (or associated department) may be adjustedaccordingly or an alert may trigger.

While the above types of information management policies 148 aredescribed as separate policies, one or more of these can be generallycombined into a single information management policy 148. For instance,a storage policy may also include or otherwise be associated with one ormore scheduling, audit, or provisioning policies or operationalparameters thereof. Moreover, while storage policies are typicallyassociated with moving and storing data, other policies may beassociated with other types of information management operations. Thefollowing is a non-exhaustive list of items that information managementpolicies 148 may specify:

-   -   schedules or other timing information, e.g., specifying when        and/or how often to perform information management operations;    -   the type of secondary copy 116 and/or copy format (e.g.,        snapshot, backup, archive, HSM, etc.);    -   a location or a class or quality of storage for storing        secondary copies 116 (e.g., one or more particular secondary        storage devices 108);    -   preferences regarding whether and how to encrypt, compress,        deduplicate, or otherwise modify or transform secondary copies        116;    -   which system components and/or network pathways (e.g., preferred        media agents 144) should be used to perform secondary storage        operations;    -   resource allocation among different computing devices or other        system components used in performing information management        operations (e.g., bandwidth allocation, available storage        capacity, etc.);    -   whether and how to synchronize or otherwise distribute files or        other data objects across multiple computing devices or hosted        services; and    -   retention information specifying the length of time primary data        112 and/or secondary copies 116 should be retained, e.g., in a        particular class or tier of storage devices, or within the        system 100.

Information management policies 148 can additionally specify or dependon historical or current criteria that may be used to determine whichrules to apply to a particular data object, system component, orinformation management operation, such as:

-   -   frequency with which primary data 112 or a secondary copy 116 of        a data object or metadata has been or is predicted to be used,        accessed, or modified;    -   time-related factors (e.g., aging information such as time since        the creation or modification of a data object);    -   deduplication information (e.g., hashes, data blocks,        deduplication block size, deduplication efficiency or other        metrics);    -   an estimated or historic usage or cost associated with different        components (e.g., with secondary storage devices 108);    -   the identity of users, applications 110, client computing        devices 102 and/or other computing devices that created,        accessed, modified, or otherwise utilized primary data 112 or        secondary copies 116;    -   a relative sensitivity (e.g., confidentiality, importance) of a        data object, e.g., as determined by its content and/or metadata;    -   the current or historical storage capacity of various storage        devices;    -   the current or historical network capacity of network pathways        connecting various components within the storage operation cell;    -   access control lists or other security information; and    -   the content of a particular data object (e.g., its textual        content) or of metadata associated with the data object.

Exemplary Storage Policy and Secondary Copy Operations

FIG. 1E includes a data flow diagram depicting performance of secondarycopy operations by an embodiment of information management system 100,according to an exemplary storage policy 148A. System 100 includes astorage manager 140, a client computing device 102 having a file systemdata agent 142A and an email data agent 142B operating thereon, aprimary storage device 104, two media agents 144A, 144B, and twosecondary storage devices 108: a disk library 108A and a tape library108B. As shown, primary storage device 104 includes primary data 112A,which is associated with a logical grouping of data associated with afile system (“file system subclient”), and primary data 112B, which is alogical grouping of data associated with email (“email subclient”). Thetechniques described with respect to FIG. 1E can be utilized inconjunction with data that is otherwise organized as well.

As indicated by the dashed box, the second media agent 144B and tapelibrary 108B are “off-site,” and may be remotely located from the othercomponents in system 100 (e.g., in a different city, office building,etc.). Indeed, “off-site” may refer to a magnetic tape located in remotestorage, which must be manually retrieved and loaded into a tape driveto be read. In this manner, information stored on the tape library 108Bmay provide protection in the event of a disaster or other failure atthe main site(s) where data is stored.

The file system subclient 112A in certain embodiments generallycomprises information generated by the file system and/or operatingsystem of client computing device 102, and can include, for example,file system data (e.g., regular files, file tables, mount points, etc.),operating system data (e.g., registries, event logs, etc.), and thelike. The e-mail subclient 112B can include data generated by an e-mailapplication operating on client computing device 102, e.g., mailboxinformation, folder information, emails, attachments, associateddatabase information, and the like. As described above, the subclientscan be logical containers, and the data included in the correspondingprimary data 112A and 112B may or may not be stored contiguously.

The exemplary storage policy 148A includes backup copy preferences orrule set 160, disaster recovery copy preferences or rule set 162, andcompliance copy preferences or rule set 164. Backup copy rule set 160specifies that it is associated with file system subclient 166 and emailsubclient 168. Each of subclients 166 and 168 are associated with theparticular client computing device 102. Backup copy rule set 160 furtherspecifies that the backup operation will be written to disk library 108Aand designates a particular media agent 144A to convey the data to disklibrary 108A. Finally, backup copy rule set 160 specifies that backupcopies created according to rule set 160 are scheduled to be generatedhourly and are to be retained for 30 days. In some other embodiments,scheduling information is not included in storage policy 148A and isinstead specified by a separate scheduling policy.

Disaster recovery copy rule set 162 is associated with the same twosubclients 166 and 168. However, disaster recovery copy rule set 162 isassociated with tape library 108B, unlike backup copy rule set 160.Moreover, disaster recovery copy rule set 162 specifies that a differentmedia agent, namely 144B, will convey data to tape library 108B.Disaster recovery copies created according to rule set 162 will beretained for 60 days and will be generated daily. Disaster recoverycopies generated according to disaster recovery copy rule set 162 canprovide protection in the event of a disaster or other catastrophic dataloss that would affect the backup copy 116A maintained on disk library108A.

Compliance copy rule set 164 is only associated with the email subclient168, and not the file system subclient 166. Compliance copies generatedaccording to compliance copy rule set 164 will therefore not includeprimary data 112A from the file system subclient 166. For instance, theorganization may be under an obligation to store and maintain copies ofemail data for a particular period of time (e.g., 10 years) to complywith state or federal regulations, while similar regulations do notapply to file system data. Compliance copy rule set 164 is associatedwith the same tape library 108B and media agent 144B as disasterrecovery copy rule set 162, although a different storage device or mediaagent could be used in other embodiments. Finally, compliance copy ruleset 164 specifies that the copies it governs will be generated quarterlyand retained for 10 years.

Secondary Copy Jobs

A logical grouping of secondary copy operations governed by a rule setand being initiated at a point in time may be referred to as a“secondary copy job” (and sometimes may be called a “backup job,” eventhough it is not necessarily limited to creating only backup copies).Secondary copy jobs may be initiated on demand as well. Steps 1-9 belowillustrate three secondary copy jobs based on storage policy 148A.

Referring to FIG. 1E, at step 1, storage manager 140 initiates a backupjob according to the backup copy rule set 160, which logically comprisesall the secondary copy operations necessary to effectuate rules 160 instorage policy 148A every hour, including steps 1-4 occurring hourly.For instance, a scheduling service running on storage manager 140accesses backup copy rule set 160 or a separate scheduling policyassociated with client computing device 102 and initiates a backup jobon an hourly basis. Thus, at the scheduled time, storage manager 140sends instructions to client computing device 102 (i.e., to both dataagent 142A and data agent 142B) to begin the backup job.

At step 2, file system data agent 142A and email data agent 142B onclient computing device 102 respond to instructions from storage manager140 by accessing and processing the respective subclient primary data112A and 112B involved in the backup copy operation, which can be foundin primary storage device 104. Because the secondary copy operation is abackup copy operation, the data agent(s) 142A, 142B may format the datainto a backup format or otherwise process the data suitable for a backupcopy.

At step 3, client computing device 102 communicates the processed filesystem data (e.g., using file system data agent 142A) and the processedemail data (e.g., using email data agent 142B) to the first media agent144A according to backup copy rule set 160, as directed by storagemanager 140. Storage manager 140 may further keep a record in managementdatabase 146 of the association between media agent 144A and one or moreof: client computing device 102, file system subclient 112A, file systemdata agent 142A, email subclient 112B, email data agent 142B, and/orbackup copy 116A.

The target media agent 144A receives the data-agent-processed data fromclient computing device 102, and at step 4 generates and conveys backupcopy 116A to disk library 108A to be stored as backup copy 116A, againat the direction of storage manager 140 and according to backup copyrule set 160. Media agent 144A can also update its index 153 to includedata and/or metadata related to backup copy 116A, such as informationindicating where the backup copy 116A resides on disk library 108A,where the email copy resides, where the file system copy resides, dataand metadata for cache retrieval, etc. Storage manager 140 may similarlyupdate its index 150 to include information relating to the secondarycopy operation, such as information relating to the type of operation, aphysical location associated with one or more copies created by theoperation, the time the operation was performed, status informationrelating to the operation, the components involved in the operation, andthe like. In some cases, storage manager 140 may update its index 150 toinclude some or all of the information stored in index 153 of mediaagent 144A. At this point, the backup job may be considered complete.After the 30-day retention period expires, storage manager 140 instructsmedia agent 144A to delete backup copy 116A from disk library 108A andindexes 150 and/or 153 are updated accordingly.

At step 5, storage manager 140 initiates another backup job for adisaster recovery copy according to the disaster recovery rule set 162.Illustratively this includes steps 5-7 occurring daily for creatingdisaster recovery copy 116B. Illustratively, and by way of illustratingthe scalable aspects and off-loading principles embedded in system 100,disaster recovery copy 116B is based on backup copy 116A and not onprimary data 112A and 112B.

At step 6, illustratively based on instructions received from storagemanager 140 at step 5, the specified media agent 1446 retrieves the mostrecent backup copy 116A from disk library 108A.

At step 7, again at the direction of storage manager 140 and asspecified in disaster recovery copy rule set 162, media agent 144B usesthe retrieved data to create a disaster recovery copy 1166 and store itto tape library 1086. In some cases, disaster recovery copy 116B is adirect, mirror copy of backup copy 116A, and remains in the backupformat. In other embodiments, disaster recovery copy 116B may be furthercompressed or encrypted, or may be generated in some other manner, suchas by using primary data 112A and 1126 from primary storage device 104as sources. The disaster recovery copy operation is initiated once a dayand disaster recovery copies 1166 are deleted after 60 days; indexes 153and/or 150 are updated accordingly when/after each informationmanagement operation is executed and/or completed. The present backupjob may be considered completed.

At step 8, storage manager 140 initiates another backup job according tocompliance rule set 164, which performs steps 8-9 quarterly to createcompliance copy 116C. For instance, storage manager 140 instructs mediaagent 144B to create compliance copy 116C on tape library 1086, asspecified in the compliance copy rule set 164.

At step 9 in the example, compliance copy 116C is generated usingdisaster recovery copy 1166 as the source. This is efficient, becausedisaster recovery copy resides on the same secondary storage device andthus no network resources are required to move the data. In otherembodiments, compliance copy 116C is instead generated using primarydata 112B corresponding to the email subclient or using backup copy 116Afrom disk library 108A as source data. As specified in the illustratedexample, compliance copies 116C are created quarterly, and are deletedafter ten years, and indexes 153 and/or 150 are kept up-to-dateaccordingly.

Exemplary Applications of Storage Policies—Information GovernancePolicies and Classification

Again referring to FIG. 1E, storage manager 140 may permit a user tospecify aspects of storage policy 148A. For example, the storage policycan be modified to include information governance policies to define howdata should be managed in order to comply with a certain regulation orbusiness objective. The various policies may be stored, for example, inmanagement database 146. An information governance policy may align withone or more compliance tasks that are imposed by regulations or businessrequirements. Examples of information governance policies might includea Sarbanes-Oxley policy, a HIPAA policy, an electronic discovery(e-discovery) policy, and so on.

Information governance policies allow administrators to obtain differentperspectives on an organization's online and offline data, without theneed for a dedicated data silo created solely for each differentviewpoint. As described previously, the data storage systems hereinbuild an index that reflects the contents of a distributed data set thatspans numerous clients and storage devices, including both primary dataand secondary copies, and online and offline copies. An organization mayapply multiple information governance policies in a top-down manner overthat unified data set and indexing schema in order to view andmanipulate the data set through different lenses, each of which isadapted to a particular compliance or business goal. Thus, for example,by applying an e-discovery policy and a Sarbanes-Oxley policy, twodifferent groups of users in an organization can conduct two verydifferent analyses of the same underlying physical set of data/copies,which may be distributed throughout the information management system.

An information governance policy may comprise a classification policy,which defines a taxonomy of classification terms or tags relevant to acompliance task and/or business objective. A classification policy mayalso associate a defined tag with a classification rule. Aclassification rule defines a particular combination of criteria, suchas users who have created, accessed or modified a document or dataobject; file or application types; content or metadata keywords; clientsor storage locations; dates of data creation and/or access; reviewstatus or other status within a workflow (e.g., reviewed orun-reviewed); modification times or types of modifications; and/or anyother data attributes in any combination, without limitation. Aclassification rule may also be defined using other classification tagsin the taxonomy. The various criteria used to define a classificationrule may be combined in any suitable fashion, for example, via Booleanoperators, to define a complex classification rule. As an example, ane-discovery classification policy might define a classification tag“privileged” that is associated with documents or data objects that (1)were created or modified by legal department staff, or (2) were sent toor received from outside counsel via email, or (3) contain one of thefollowing keywords: “privileged” or “attorney” or “counsel,” or otherlike terms. Accordingly, all these documents or data objects will beclassified as “privileged.”

One specific type of classification tag, which may be added to an indexat the time of indexing, is an “entity tag.” An entity tag may be, forexample, any content that matches a defined data mask format. Examplesof entity tags might include, e.g., social security numbers (e.g., anynumerical content matching the formatting mask XXX-XX-XXXX), credit cardnumbers (e.g., content having a 13-16 digit string of numbers), SKUnumbers, product numbers, etc. A user may define a classification policyby indicating criteria, parameters or descriptors of the policy via agraphical user interface, such as a form or page with fields to befilled in, pull-down menus or entries allowing one or more of severaloptions to be selected, buttons, sliders, hypertext links or other knownuser interface tools for receiving user input, etc. For example, a usermay define certain entity tags, such as a particular product number orproject ID. In some implementations, the classification policy can beimplemented using cloud-based techniques. For example, the storagedevices may be cloud storage devices, and the storage manager 140 mayexecute cloud service provider API over a network to classify datastored on cloud storage devices.

Restore Operations from Secondary Copies

While not shown in FIG. 1E, at some later point in time, a restoreoperation can be initiated involving one or more of secondary copies116A, 116B, and 116C. A restore operation logically takes a selectedsecondary copy 116, reverses the effects of the secondary copy operationthat created it, and stores the restored data to primary storage where aclient computing device 102 may properly access it as primary data. Amedia agent 144 and an appropriate data agent 142 (e.g., executing onthe client computing device 102) perform the tasks needed to complete arestore operation. For example, data that was encrypted, compressed,and/or deduplicated in the creation of secondary copy 116 will becorrespondingly rehydrated (reversing deduplication), uncompressed, andunencrypted into a format appropriate to primary data. Metadata storedwithin or associated with the secondary copy 116 may be used during therestore operation. In general, restored data should be indistinguishablefrom other primary data 112. Preferably, the restored data has fullyregained the native format that may make it immediately usable byapplication 110.

As one example, a user may manually initiate a restore of backup copy116A, e.g., by interacting with user interface 158 of storage manager140 or with a web-based console with access to system 100. Storagemanager 140 may accesses data in its index 150 and/or managementdatabase 146 (and/or the respective storage policy 148A) associated withthe selected backup copy 116A to identify the appropriate media agent144A and/or secondary storage device 108A where the secondary copyresides. The user may be presented with a representation (e.g., stub,thumbnail, listing, etc.) and metadata about the selected secondarycopy, in order to determine whether this is the appropriate copy to berestored, e.g., date that the original primary data was created. Storagemanager 140 will then instruct media agent 144A and an appropriate dataagent 142 on the target client computing device 102 to restore secondarycopy 116A to primary storage device 104. A media agent may be selectedfor use in the restore operation based on a load balancing algorithm, anavailability based algorithm, or other criteria. The selected mediaagent, e.g., 144A, retrieves secondary copy 116A from disk library 108A.For instance, media agent 144A may access its index 153 to identify alocation of backup copy 116A on disk library 108A, or may accesslocation information residing on disk library 108A itself.

In some cases a backup copy 116A that was recently created or accessed,may be cached to speed up the restore operation. In such a case, mediaagent 144A accesses a cached version of backup copy 116A residing inindex 153, without having to access disk library 108A for some or all ofthe data. Once it has retrieved backup copy 116A, the media agent 144Acommunicates the data to the requesting client computing device 102.Upon receipt, file system data agent 142A and email data agent 142B mayunpack (e.g., restore from a backup format to the native applicationformat) the data in backup copy 116A and restore the unpackaged data toprimary storage device 104. In general, secondary copies 116 may berestored to the same volume or folder in primary storage device 104 fromwhich the secondary copy was derived; to another storage location orclient computing device 102; to shared storage, etc. In some cases, thedata may be restored so that it may be used by an application 110 of adifferent version/vintage from the application that created the originalprimary data 112.

Exemplary Secondary Copy Formatting

The formatting and structure of secondary copies 116 can vary dependingon the embodiment. In some cases, secondary copies 116 are formatted asa series of logical data units or “chunks” (e.g., 512 MB, 1 GB, 2 GB, 4GB, or 8 GB chunks). This can facilitate efficient communication andwriting to secondary storage devices 108, e.g., according to resourceavailability. For example, a single secondary copy 116 may be written ona chunk-by-chunk basis to one or more secondary storage devices 108. Insome cases, users can select different chunk sizes, e.g., to improvethroughput to tape storage devices. Generally, each chunk can include aheader and a payload. The payload can include files (or other dataunits) or subsets thereof included in the chunk, whereas the chunkheader generally includes metadata relating to the chunk, some or all ofwhich may be derived from the payload. For example, during a secondarycopy operation, media agent 144, storage manager 140, or other componentmay divide files into chunks and generate headers for each chunk byprocessing the files. Headers can include a variety of information suchas file and/or volume identifier(s), offset(s), and/or other informationassociated with the payload data items, a chunk sequence number, etc.Importantly, in addition to being stored with secondary copy 116 onsecondary storage device 108, chunk headers can also be stored to index153 of the associated media agent(s) 144 and/or to index 150 associatedwith storage manager 140. This can be useful for providing fasterprocessing of secondary copies 116 during browsing, restores, or otheroperations. In some cases, once a chunk is successfully transferred to asecondary storage device 108, the secondary storage device 108 returnsan indication of receipt, e.g., to media agent 144 and/or storagemanager 140, which may update their respective indexes 153, 150accordingly. During restore, chunks may be processed (e.g., by mediaagent 144) according to the information in the chunk header toreassemble the files.

Data can also be communicated within system 100 in data channels thatconnect client computing devices 102 to secondary storage devices 108.These data channels can be referred to as “data streams,” and multipledata streams can be employed to parallelize an information managementoperation, improving data transfer rate, among other advantages. Exampledata formatting techniques including techniques involving datastreaming, chunking, and the use of other data structures in creatingsecondary copies are described in U.S. Pat. Nos. 7,315,923, 8,156,086,and 8,578,120.

FIGS. 1F and 1G are diagrams of example data streams 170 and 171,respectively, which may be employed for performing informationmanagement operations. Referring to FIG. 1F, data agent 142 forms datastream 170 from source data associated with a client computing device102 (e.g., primary data 112). Data stream 170 is composed of multiplepairs of stream header 172 and stream data (or stream payload) 174. Datastreams 170 and 171 shown in the illustrated example are for asingle-instanced storage operation, and a stream payload 174 thereforemay include both single-instance (SI) data and/or non-SI data. A streamheader 172 includes metadata about the stream payload 174. This metadatamay include, for example, a length of the stream payload 174, anindication of whether the stream payload 174 is encrypted, an indicationof whether the stream payload 174 is compressed, an archive fileidentifier (ID), an indication of whether the stream payload 174 issingle instanceable, and an indication of whether the stream payload 174is a start of a block of data.

Referring to FIG. 1G, data stream 171 has the stream header 172 andstream payload 174 aligned into multiple data blocks. In this example,the data blocks are of size 64 KB. The first two stream header 172 andstream payload 174 pairs comprise a first data block of size 64 KB. Thefirst stream header 172 indicates that the length of the succeedingstream payload 174 is 63 KB and that it is the start of a data block.The next stream header 172 indicates that the succeeding stream payload174 has a length of 1 KB and that it is not the start of a new datablock. Immediately following stream payload 174 is a pair comprising anidentifier header 176 and identifier data 178. The identifier header 176includes an indication that the succeeding identifier data 178 includesthe identifier for the immediately previous data block. The identifierdata 178 includes the identifier that the data agent 142 generated forthe data block. The data stream 171 also includes other stream header172 and stream payload 174 pairs, which may be for SI data and/or non-SIdata.

FIG. 1H is a diagram illustrating data structures 180 that may be usedto store blocks of SI data and non-SI data on a storage device (e.g.,secondary storage device 108). According to certain embodiments, datastructures 180 do not form part of a native file system of the storagedevice. Data structures 180 include one or more volume folders 182, oneor more chunk folders 184/185 within the volume folder 182, and multiplefiles within chunk folder 184. Each chunk folder 184/185 includes ametadata file 186/187, a metadata index file 188/189, one or morecontainer files 190/191/193, and a container index file 192/194.Metadata file 186/187 stores non-SI data blocks as well as links to SIdata blocks stored in container files. Metadata index file 188/189stores an index to the data in the metadata file 186/187. Containerfiles 190/191/193 store SI data blocks. Container index file 192/194stores an index to container files 190/191/193. Among other things,container index file 192/194 stores an indication of whether acorresponding block in a container file 190/191/193 is referred to by alink in a metadata file 186/187. For example, data block B2 in thecontainer file 190 is referred to by a link in metadata file 187 inchunk folder 185. Accordingly, the corresponding index entry incontainer index file 192 indicates that data block B2 in container file190 is referred to. As another example, data block B1 in container file191 is referred to by a link in metadata file 187, and so thecorresponding index entry in container index file 192 indicates thatthis data block is referred to.

As an example, data structures 180 illustrated in FIG. 1H may have beencreated as a result of separate secondary copy operations involving twoclient computing devices 102. For example, a first secondary copyoperation on a first client computing device 102 could result in thecreation of the first chunk folder 184, and a second secondary copyoperation on a second client computing device 102 could result in thecreation of the second chunk folder 185. Container files 190/191 in thefirst chunk folder 184 would contain the blocks of SI data of the firstclient computing device 102. If the two client computing devices 102have substantially similar data, the second secondary copy operation onthe data of the second client computing device 102 would result in mediaagent 144 storing primarily links to the data blocks of the first clientcomputing device 102 that are already stored in the container files190/191. Accordingly, while a first secondary copy operation may resultin storing nearly all of the data subject to the operation, subsequentsecondary storage operations involving similar data may result insubstantial data storage space savings, because links to already storeddata blocks can be stored instead of additional instances of datablocks.

If the operating system of the secondary storage computing device 106 onwhich media agent 144 operates supports sparse files, then when mediaagent 144 creates container files 190/191/193, it can create them assparse files. A sparse file is a type of file that may include emptyspace (e.g., a sparse file may have real data within it, such as at thebeginning of the file and/or at the end of the file, but may also haveempty space in it that is not storing actual data, such as a contiguousrange of bytes all having a value of zero). Having container files190/191/193 be sparse files allows media agent 144 to free up space incontainer files 190/191/193 when blocks of data in container files190/191/193 no longer need to be stored on the storage devices. In someexamples, media agent 144 creates a new container file 190/191/193 whena container file 190/191/193 either includes 100 blocks of data or whenthe size of the container file 190 exceeds 50 MB. In other examples,media agent 144 creates a new container file 190/191/193 when acontainer file 190/191/193 satisfies other criteria (e.g., it containsfrom approx. 100 to approx. 1000 blocks or when its size exceedsapproximately 50 MB to 1 GB). In some cases, a file on which a secondarycopy operation is performed may comprise a large number of data blocks.For example, a 100 MB file may comprise 400 data blocks of size 256 KB.If such a file is to be stored, its data blocks may span more than onecontainer file, or even more than one chunk folder. As another example,a database file of 20 GB may comprise over 40,000 data blocks of size512 KB. If such a database file is to be stored, its data blocks willlikely span multiple container files, multiple chunk folders, andpotentially multiple volume folders. Restoring such files may requireaccessing multiple container files, chunk folders, and/or volume foldersto obtain the requisite data blocks.

Using Backup Data for Replication and Disaster Recovery (“LiveSynchronization”)

There is an increased demand to off-load resource intensive informationmanagement tasks (e.g., data replication tasks) away from productiondevices (e.g., physical or virtual client computing devices) in order tomaximize production efficiency. At the same time, enterprises expectaccess to readily-available up-to-date recovery copies in the event offailure, with little or no production downtime.

FIG. 2A illustrates a system 200 configured to address these and otherissues by using backup or other secondary copy data to synchronize asource subsystem 201 (e.g., a production site) with a destinationsubsystem 203 (e.g., a failover site). Such a technique can be referredto as “live synchronization” and/or “live synchronization replication.”In the illustrated embodiment, the source client computing devices 202 ainclude one or more virtual machines (or “VMs”) executing on one or morecorresponding VM host computers 205 a, though the source need not bevirtualized. The destination site 203 may be at a location that isremote from the production site 201, or may be located in the same datacenter, without limitation. One or more of the production site 201 anddestination site 203 may reside at data centers at known geographiclocations, or alternatively may operate “in the cloud.”

The synchronization can be achieved by generally applying an ongoingstream of incremental backups from the source subsystem 201 to thedestination subsystem 203, such as according to what can be referred toas an “incremental forever” approach. FIG. 2A illustrates an embodimentof a data flow which may be orchestrated at the direction of one or morestorage managers (not shown). At step 1, the source data agent(s) 242 aand source media agent(s) 244 a work together to write backup or othersecondary copies of the primary data generated by the source clientcomputing devices 202 a into the source secondary storage device(s) 208a. At step 2, the backup/secondary copies are retrieved by the sourcemedia agent(s) 244 a from secondary storage. At step 3, source mediaagent(s) 244 a communicate the backup/secondary copies across a networkto the destination media agent(s) 244 b in destination subsystem 203.

As shown, the data can be copied from source to destination in anincremental fashion, such that only changed blocks are transmitted, andin some cases multiple incremental backups are consolidated at thesource so that only the most current changed blocks are transmitted toand applied at the destination. An example of live synchronization ofvirtual machines using the “incremental forever” approach is found inU.S. Patent Application No. 62/265,339 entitled “Live Synchronizationand Management of Virtual Machines across Computing and VirtualizationPlatforms and Using Live Synchronization to Support Disaster Recovery.”Moreover, a deduplicated copy can be employed to further reduce networktraffic from source to destination. For instance, the system can utilizethe deduplicated copy techniques described in U.S. Pat. No. 9,239,687,entitled “Systems and Methods for Retaining and Using Data BlockSignatures in Data Protection Operations.”

At step 4, destination media agent(s) 244 b write the receivedbackup/secondary copy data to the destination secondary storagedevice(s) 208 b. At step 5, the synchronization is completed when thedestination media agent(s) and destination data agent(s) 242 b restorethe backup/secondary copy data to the destination client computingdevice(s) 202 b. The destination client computing device(s) 202 b may bekept “warm” awaiting activation in case failure is detected at thesource. This synchronization/replication process can incorporate thetechniques described in U.S. patent application Ser. No. 14/721,971,entitled “Replication Using Deduplicated Secondary Copy Data.”

Where the incremental backups are applied on a frequent, on-going basis,the synchronized copies can be viewed as mirror or replication copies.Moreover, by applying the incremental backups to the destination site203 using backup or other secondary copy data, the production site 201is not burdened with the synchronization operations. Because thedestination site 203 can be maintained in a synchronized “warm” state,the downtime for switching over from the production site 201 to thedestination site 203 is substantially less than with a typical restorefrom secondary storage. Thus, the production site 201 may flexibly andefficiently fail over, with minimal downtime and with relativelyup-to-date data, to a destination site 203, such as a cloud-basedfailover site. The destination site 203 can later be reversesynchronized back to the production site 201, such as after repairs havebeen implemented or after the failure has passed.

Integrating with the Cloud Using File System Protocols

Given the ubiquity of cloud computing, it can be increasingly useful toprovide data protection and other information management services in ascalable, transparent, and highly plug-able fashion. FIG. 2B illustratesan information management system 200 having an architecture thatprovides such advantages, and incorporates use of a standard file systemprotocol between primary and secondary storage subsystems 217, 218. Asshown, the use of the network file system (NFS) protocol (or any anotherappropriate file system protocol such as that of the Common InternetFile System (CIFS)) allows data agent 242 to be moved from the primarystorage subsystem 217 to the secondary storage subsystem 218. Forinstance, as indicated by the dashed box 206 around data agent 242 andmedia agent 244, data agent 242 can co-reside with media agent 244 onthe same server (e.g., a secondary storage computing device such ascomponent 106), or in some other location in secondary storage subsystem218.

Where NFS is used, for example, secondary storage subsystem 218allocates an NFS network path to the client computing device 202 or toone or more target applications 210 running on client computing device202. During a backup or other secondary copy operation, the clientcomputing device 202 mounts the designated NFS path and writes data tothat NFS path. The NFS path may be obtained from NFS path data 215stored locally at the client computing device 202, and which may be acopy of or otherwise derived from NFS path data 219 stored in thesecondary storage subsystem 218.

Write requests issued by client computing device(s) 202 are received bydata agent 242 in secondary storage subsystem 218, which translates therequests and works in conjunction with media agent 244 to process andwrite data to a secondary storage device(s) 208, thereby creating abackup or other secondary copy. Storage manager 240 can include apseudo-client manager 217, which coordinates the process by, among otherthings, communicating information relating to client computing device202 and application 210 (e.g., application type, client computing deviceidentifier, etc.) to data agent 242, obtaining appropriate NFS path datafrom the data agent 242 (e.g., NFS path information), and deliveringsuch data to client computing device 202.

Conversely, during a restore or recovery operation client computingdevice 202 reads from the designated NFS network path, and the readrequest is translated by data agent 242. The data agent 242 then workswith media agent 244 to retrieve, re-process (e.g., re-hydrate,decompress, decrypt), and forward the requested data to client computingdevice 202 using NFS.

By moving specialized software associated with system 200 such as dataagent 242 off the client computing devices 202, the illustrativearchitecture effectively decouples the client computing devices 202 fromthe installed components of system 200, improving both scalability andplug-ability of system 200. Indeed, the secondary storage subsystem 218in such environments can be treated simply as a read/write NFS targetfor primary storage subsystem 217, without the need for informationmanagement software to be installed on client computing devices 202. Asone example, an enterprise implementing a cloud production computingenvironment can add VM client computing devices 202 without installingand configuring specialized information management software on theseVMs. Rather, backups and restores are achieved transparently, where thenew VMs simply write to and read from the designated NFS path. Anexample of integrating with the cloud using file system protocols orso-called “infinite backup” using NFS share is found in U.S. PatentApplication No. 62/294,920, entitled “Data Protection Operations Basedon Network Path Information.” Examples of improved data restorationscenarios based on network-path information, including using storedbackups effectively as primary data sources, may be found in U.S. PatentApplication No. 62/297,057, entitled “Data Restoration Operations Basedon Network Path Information.”

Highly Scalable Managed Data Pool Architecture

Enterprises are seeing explosive data growth in recent years, often fromvarious applications running in geographically distributed locations.FIG. 2C shows a block diagram of an example of a highly scalable,managed data pool architecture useful in accommodating such data growth.The illustrated system 200, which may be referred to as a “web-scale”architecture according to certain embodiments, can be readilyincorporated into both open compute/storage and common-cloudarchitectures.

The illustrated system 200 includes a grid 245 of media agents 244logically organized into a control tier 231 and a secondary or storagetier 233. Media agents assigned to the storage tier 233 can beconfigured to manage a secondary storage pool 208 as a deduplicationstore, and be configured to receive client write and read requests fromthe primary storage subsystem 217, and direct those requests to thesecondary tier 233 for servicing. For instance, media agents CMA1-CMA3in the control tier 231 maintain and consult one or more deduplicationdatabases 247, which can include deduplication information (e.g., datablock hashes, data block links, file containers for deduplicated files,etc.) sufficient to read deduplicated files from secondary storage pool208 and write deduplicated files to secondary storage pool 208. Forinstance, system 200 can incorporate any of the deduplication systemsand methods shown and described in U.S. Pat. No. 9,020,900, entitled“Distributed Deduplicated Storage System,” and U.S. Pat. Pub. No.2014/0201170, entitled “High Availability Distributed DeduplicatedStorage System.”

Media agents SMA1-SMA6 assigned to the secondary tier 233 receive writeand read requests from media agents CMA1-CMA3 in control tier 231, andaccess secondary storage pool 208 to service those requests. Mediaagents CMA1-CMA3 in control tier 231 can also communicate with secondarystorage pool 208, and may execute read and write requests themselves(e.g., in response to requests from other control media agentsCMA1-CMA3) in addition to issuing requests to media agents in secondarytier 233. Moreover, while shown as separate from the secondary storagepool 208, deduplication database(s) 247 can in some cases reside instorage devices in secondary storage pool 208.

As shown, each of the media agents 244 (e.g., CMA1-CMA3, SMA1-SMA6,etc.) in grid 245 can be allocated a corresponding dedicated partition251A-251I, respectively, in secondary storage pool 208. Each partition251 can include a first portion 253 containing data associated with(e.g., stored by) media agent 244 corresponding to the respectivepartition 251. System 200 can also implement a desired level ofreplication, thereby providing redundancy in the event of a failure of amedia agent 244 in grid 245. Along these lines, each partition 251 canfurther include a second portion 255 storing one or more replicationcopies of the data associated with one or more other media agents 244 inthe grid.

System 200 can also be configured to allow for seamless addition ofmedia agents 244 to grid 245 via automatic configuration. As oneillustrative example, a storage manager (not shown) or other appropriatecomponent may determine that it is appropriate to add an additional nodeto control tier 231, and perform some or all of the following: (i)assess the capabilities of a newly added or otherwise availablecomputing device as satisfying a minimum criteria to be configured as orhosting a media agent in control tier 231; (ii) confirm that asufficient amount of the appropriate type of storage exists to supportan additional node in control tier 231 (e.g., enough disk drive capacityexists in storage pool 208 to support an additional deduplicationdatabase 247); (iii) install appropriate media agent software on thecomputing device and configure the computing device according to apre-determined template; (iv) establish a partition 251 in the storagepool 208 dedicated to the newly established media agent 244; and (v)build any appropriate data structures (e.g., an instance ofdeduplication database 247). An example of highly scalable managed datapool architecture or so-called web-scale architecture for storage anddata management is found in U.S. Patent Application No. 62/273,286entitled “Redundant and Robust Distributed Deduplication Data StorageSystem.”

The embodiments and components thereof disclosed in FIGS. 2A, 2B, and2C, as well as those in FIGS. 1A-1H, may be implemented in anycombination and permutation to satisfy data storage management andinformation management needs at one or more locations and/or datacenters.

Cross-Hypervisor Live-Mount of Backed Up Virtual Machine Data

Illustrative systems and methods for “cross-hypervisor live-mount”enable a virtual machine (“VM”) to be powered up at any hypervisorregardless of hypervisor type based on live-mounting VM data that waspreviously backed up into a hypervisor-independent format by ablock-level backup operation.

FIG. 3 is a block diagram illustrating some salient portions of a system300 for cross-hypervisor live-mount of backed up virtual machine dataaccording to an illustrative embodiment of the present invention. FIG. 3depicts: virtual machine host 301-A, comprising source virtual machine302 and source hypervisor 322-A in communication with virtual disk 312in storage device 104; virtual machine host 301-B, comprising targetvirtual machine 333 and target hypervisor 322-B in communication withbackup proxy machine 306; backup proxy machine 306 comprising hypervisormetadata copy 315 and hypervisor-independent virtual machine backup copy316, both of which were generated in a hypervisor-independent back-levelbackup operation as shown by the dotted arrows; and storage manager 340in communication with backup proxy machine 306. The bold bi-directionalarrow between target hypervisor 322-B and backup proxy machine 306depicts the illustrative “cross-hypervisor live-mount of backed upvirtual machine data” feature according to an illustrative embodiment.

System 300 is a data storage management system that comprisescapabilities for live-mounting backed up VM data to one or more VMs overany kind of hypervisor, regardless of the type of hypervisor used by theoriginal source VM that originated the backed up data. System 300 thusprovides the so-called “cross-hypervisor live-mount of backed up VMdata” feature according to one or more illustrative embodiments. System300 illustratively comprises storage manager 340 and backup proxymachine 306 and/or data storage management appliance 790, and in someembodiments does not comprise VM host 301-A, storage 104-A, or VM host301-B. In some embodiments, VM host 301-B is part of system 300. Incloud-based computing environments such as the example in FIG. 6, system300 comprises certain components within backup proxy VM 606 and Host B,but does not comprise backup proxy VM 606 and Host B, which arethemselves implemented as cloud-based VMs. Cloud-based processing andstorage resources are not part of system 300 when they are supplied by acloud service providers. However, they are used in conjunction withother components of system 300 to implement the illustrativecross-hypervisor live-mount of backed up VM data.

Storage device 104-A stores “live” production data, such as one or morevirtual disks 312 used by corresponding VMs 302. Storage devices forvirtual disks are well known in the art. Storage device 104-A isreferred to as a primary storage device, because it stores and serves“live” production data. Primary storage device 104-A is accessible byone or more VM hosts 301-A and/or other computing devices in system 300.

Virtual machine host (“VM host”) 301-A is a computing device thatcomprises one or more processors and computer memory. VM host 301-Aexecutes source hypervisor 322-A, which in turn hosts one or morevirtual machines 302. VM host 301-A is illustratively used here in a“live” production environment, in contrast to a backup, disasterrecovery, and/or test environment for VM host 301-B. VM hosts andhypervisors are well known in the art.

Virtual machine host 301-B is a computing device that comprises one ormore processors and computer memory. VM host 301-B executes targethypervisor 322-B, which in turn hosts one or more target virtualmachines 333. According to the illustrative embodiments, VM host 301-Bis used in a backup, disaster recovery, and/or test environment forhosting one or more target VMs 333.

Virtual machine (“VM”) 302 is a virtual machine that executes on VM host301-A over hypervisor 322-A. VM 302 provides a computing platform forexecuting one or more applications and/or file systems 110. Virtualmachines such as VM 302 are well known in the art and are described inmore detail elsewhere herein. Illustratively, each VM 302 reads, writes,deletes, and/or uses data in a corresponding virtual disk 312. BecauseVM 302 is the source and originator of data that is backed up andlive-mounted for use by target VM 333, VM 302 is sometimes referred toherein as the “source VM.” Thus, source VM 302 is said to be “backedup,” because the data in its associated virtual disk (e.g., 312) wasbacked up, resulting in copies 315 and 316. Therefore, when we referherein to a backed up VM, its payload data as well as hypervisor-relatedmetadata have been backed up in a prior operation and the backup copiesreside in secondary storage.

Backup proxy machine (“backup proxy” or “proxy machine”) 306 is acomputing device that comprises one or more processors and computermemory. According to the illustrative embodiment, backup proxy 306 isconfigured to enable the illustrative cross-hypervisor live-mount ofbacked VM data. The features and capabilities of backup proxy 306 aredescribed in more detail in FIG. 4 and FIG. 5. Backup proxy 306comprises data storage resources for storing copies generated byhypervisor-independent block-level operations from source VM 302, e.g.,copies 315 and 316, and shown in another figure, also comprises cachestorage resources that are actively used by the illustrativecross-hypervisor live-mount feature.

Virtual disk 312 is the data source and repository for VM 302 anduniquely corresponds to VM 302. Virtual disk 312 is data storage thatcomprises data accessed (read, write, use, delete) by corresponding VM302. Depending on the virtual machine technology, virtual disk 312 isknown in the art as VMDK, VHD, or other terminology (e.g., virtualmachine disk files (“VMDK”) in VMware lingo; virtual hard disk (“VHD”)image files in Microsoft lingo; etc. without limitation). As is wellknown in the art, the use of the term “vmdk” is commonly used to referto a VM's virtual disk and does not necessarily a VMWare environment.Herein, we generally use the term “virtual disk.” Virtual diskscorresponding to VMs are well known in the art. Here, virtual disk 412is stored in a primary storage device 104-A. Like VM host 301-A, virtualdisks 312 and the storage devices 104 that host them are well known inthe art and can be configured in a data center or in a cloud computingenvironment without limitation.

Dotted arrows from virtual disk 312 collectively depict ahypervisor-independent block-level backup operation from virtual disk312 resulting in hypervisor metadata copy 315 and hypervisor-independentVM block-level backup copy 316. This operation is described in detail inU.S. Pat. Pub. No. 2017-0262204 A1, entitled “Hypervisor-IndependentBlock-Level Live Browse for Access to Backed up Virtual Machine (VM)Data and Hypervisor-Free File-Level Recovery (Block-LevelPseudo-Mount)”, which is incorporated by reference herein. There is nolimitation how many hypervisor-independent block-level backup operationsare run or in how many copies 315 and 316 result therefrom and arestored to backup proxy machine 306. The illustrative cross-hypervisorlive-mount feature described herein presupposes the existence of one ormore hypervisor-independent VM block-level backup copies 316, which areto be live-mounted according to the illustrative embodiments. Someembodiments also use hypervisor metadata copy 315 when initiallyconfiguring a target VM 333.

Hypervisor metadata copy 315 is generated in the hypervisor-independentblock-level backup operation illustrated by the dotted arrows. Copy 315generally comprises metadata collected from hypervisor 322 and/orvirtual disk 312 in the course of the backup operation and is storedseparately from hypervisor-independent VM block-level backup copy 316.Some embodiments use hypervisor metadata copy 315 when initiallyconfiguring a target VM 333, as described in more detail elsewhereherein.

Hypervisor-independent VM block-level backup copy (“backup copy”) 316 isgenerated in the hypervisor-independent block-level backup operationillustrated by the dotted arrows. Backup copy 316 generally comprisespayload data collected from virtual disk 312 in the course of the backupoperation and is stored separately from hypervisor metadata copy 315.Backup copy 316 is said to be “cross-hypervisor live-mounted” accordingto the illustrative embodiments. Notably, in some embodiments the samebackup copy 316 is live-mounted to a plurality of target VMs 333, whichmay reside on the same or different target hosts 301-B. Thus, one backupcopy 316 can be used efficiently to “feed” multiple target VMs 333,which can be used for different purposes, e.g., checking and testing theintegrity of backup copy 316, simulating a disaster recovery scenario,testing a candidate cloud computing environment, etc., withoutlimitation.

Source Hypervisor 322-A and target hypervisor 322-B are well known inthe art. According to the illustrative embodiments, they are ofdifferent types. The illustrative cross-hypervisor live-mount feature isdesigned to allow for differences between the source and targethypervisors without converting hypervisor metadata from one type toanother. Rather, the source hypervisor 322-A's metadata is stripped outduring the hypervisor-independent block-level backup operation (seeabove) and stored in copy 315 apart from VM payload data stored inbackup copy 316. Backup copy 316 is then live-mounted to target VM 333,which executes on a target hypervisor 322-B of any type, whether thesame or different from source hypervisor 322-A. In some embodiments,metadata copy 315 is used in part to extract configuration informationabout source hypervisor 322-A that can be used in configuring targethypervisor 322-B and/or target VM 333. This is useful when the targethypervisor has features or configuration parameters that are analogousto source hypervisor 322-A and could be mimicked when target hypervisor322-B is configured. When no such similarities are found between sourceand target hypervisor, target hypervisor 322-B is set up with defaultvalues without regard to information metadata copy 315. More details aregiven in other figures herein.

Target virtual machine (“VM”) 333 is a virtual machine that executes onVM host 301-B over hypervisor 322-B. VM 333 provides a computingenvironment for live-mounting backup copy 316 that originated withsource VM 302. Illustratively, VM 333 reads, writes, deletes, and/oruses data in a corresponding virtual disk 412 (not shown in the presentfigure).

The bold bi-directional arrow between target hypervisor 322-B and backupproxy machine 306 depicts the illustrative cross-hypervisor live-mountfeature for backed up virtual machine data according to an illustrativeembodiment.

Storage manager 340 is analogous to storage manager 140 and furthercomprises additional features for operating in system 300. Storagemanager 340 executes on an underlying computing device that comprisesone or more processors and computer memory. In some embodiments storagemanager 340 is said to comprise one or more processors and computermemory. For example, storage manager 340 manages and controls storageoperations within system 300, such as backups and restores. More detailsare given in other figures herein.

System 300 is shown here in a simplified form to ease the reader'sunderstanding of the present disclosure. In other embodiments, system300 comprises any number of VM hosts 301, VMs 302 and 333, andcorresponding virtual disks 312 and 412, as well as any number of backupproxies 306 and backup copies 316, without limitation.

FIG. 4 is a block diagram illustrating some salient details of system300, including storage manager 440 and some components of backup proxymachine 306. FIG. 4 depicts: VM host 301-B comprising target hypervisor322-B and target VM 333; backup proxy machine 306 comprising backupcopies 315 and 316, cache storage 404, virtual disk 412, virtual serverdata agent 442, and media agent 444; and storage manager 340 incommunication with data agent 442 and media agent 444, and comprisingmanagement database 146.

VM host 301-B, target hypervisor 322-B, and target VM 333 were describedin another figure herein. Likewise, storage manager 340 and backupcopies 315 and 316 were described elsewhere herein. Management database146, which is a logical part of storage manager 340 is described in moredetail elsewhere herein.

Backup proxy 306 was described in part in other figures herein.According to the pictured embodiment, backup proxy 306 comprises backupcopies 315 and 316, cache storage 404, virtual disk 412, virtual serverdata agent 442, and media agent 444, but alternative embodiments arepossible in which these components reside separately or in differentgroupings. For example, in some alternative embodiments data agent 442executes on a computing device that is separate from backup proxy 306.For example, in some alternative embodiments copies 315 and 316 arestored in a secondary storage device 108 (not shown here) that isseparate from backup proxy 306 and in communication with media agent444. Preferably, cache storage 404 co-resides with media agent 444 onthe same computing device, because cache storage 404 is closelyassociated with media agent 444 and needs to be quickly accessible forperformance reasons in serving data therefrom to one or more target VMs333. In all embodiments, the associations, relationships, andcommunication pathways pictured here remain, but the physicaldistribution of these functional components may differ from what FIG. 4depicts.

Cache storage 404 is a data storage resource configured in backup proxy306. Cache storage 404 plays a role in the illustrative cross-hypervisorlive-mount of backed up virtual machine data” feature by hosting one ormore virtual disks 412 that correspond to respective target VMs 333.Physically, cache storage 404 is co-located with storage resources (notshown in the present figure) for copies 315 and 316. As explainedelsewhere herein, cache 404 is configured in some embodiments to be offlexible size, so that it can grow with heavier use or shrink when morestorage space is needed for additional backup copies 315 and/or 316. Inother embodiments cache storage 404 is fixed in size within any givenbackup proxy 306, though it can be configured to any size withoutlimitation depending on how much storage is available for backup proxy306.

Virtual server data agent (“VSA”) 442 is a data agent analogous to dataagent 142, and comprises enhancements for operating in system 300. VSA442 is a data agent for backing up and restoring virtual machines. Forthe cross-hypervisor live-mount feature, VSA 442 performs certain tasks,such as exporting/exposing cache 404 to target hypervisor 322-B, causinga target VM 333 to be registered with target hypervisor 322-B, and otheroperations without limitation. VSA 442 communicates with storage manager340 via communication pathway 114 as depicted by the bidirectionalarrows therebetween. More details are given in the flow chart figureselsewhere herein.

Media agent 444 is analogous to media agent 144 and additionallycomprises enhancements for operating in system 300. Media agent isgenerally responsible for storing and recovering secondary copies. Forthe cross-hypervisor live-mount feature, media agent 444 sets up andmanages cache storage 404 and performs certain other tasks, such asassociating a given backup copy 316 with a target VM 333; interceptingread and write requests issued by target VM 333, tracking which datablocks are newly written, and other operations without limitations.Media agent 444 communicates with storage manager 340 via communicationpathway 114 as depicted by the bidirectional arrows therebetween. Moredetails are given in the flow chart figures elsewhere herein.

The bold bi-directional arrow between target hypervisor 322-B and mediaagent 444 in backup proxy 306 depicts the cross-hypervisor live-mount ofbacked up virtual machine data feature according to an illustrativeembodiment. The dotted bi-directional arrow between backup copy 316 andvirtual disk 412 represents an association therebetween that enablesmedia agent 444 to populate virtual disk 412 with data blocks retrievedfrom backup copy 316. The solid unidirectional arrow from backup 316 tomedia agent 444 represents how data flows from backup copy 316 to mediaagent 444 during the illustrative cross-hypervisor live-mount of backedup virtual machine data feature. The dashed unidirectional arrow frommetadata copy 315 to media agent 444 represents the optional use ofsource metadata to configure a target VM 333. The solid bi-directionalarrow between virtual disk 412 in cache 404 and media agent 444represents data being written to and read from virtual disk 412 whenbackup copy 316 is live-mounted to target VM 333. More details are givenin the flow chart figures elsewhere herein.

FIG. 5 is a block diagram illustrating some salient details of system300 configured with a plurality of distinct target virtual machineslive-mounted to the same virtual machine backup copy. FIG. 5 depicts thesame components shown in FIG. 4, except that storage manager 340 is notshown in the present figure; additionally, a plurality of target VMs 333(e.g., 333-1 . . . 333-N) execute over target hypervisor 322-b, andcache storage 404 hosts a plurality of virtual disks 412 (e.g., 412-1 .. . 412-N), each virtual disk 412 uniquely corresponding to a respectivetarget VM 333.

The dotted bi-directional arrows between backup copy 316 and eachvirtual disk 412 (e.g., 412-1 . . . 412-N) represent associationstherebetween that enable media agent 444 to populate virtual disks 412with data blocks retrieved from backup copy 316 when a plurality oftarget VMs 333 have live-mounted the same backup copy 316.

The solid bi-directional arrows between each virtual disk 412 in cache404 and media agent 444 represents data being written to and read fromeach virtual disk 412 when a plurality of target VMs 333 havelive-mounted the same backup copy 316. According to the illustrativeembodiments, the contents of each virtual disk 412 is treatedindependently of the other virtual disks 412 in cache 404, regardless ofwhether the same or different data blocks are read and/or writtenthereto by the plurality of target VMs 333. Thus, each virtual disk 412uniquely corresponds to and supports a certain target VM 333, withoutregard to the contents of other virtual disks 412 within the same cache404 and associated with the same backup copy 316.

There is no limit to how many target VMs 333 and corresponding virtualdisks 412 can be configured in a system 300. Moreover, there is no limitto how many distinct VM hosts 301-B can be configured in system 300.There is also no limit on how many distinct backup copies 316 can belive-mounted at any given time by the cross-hypervisor live-mountfeature.

FIG. 6 is a block diagram illustrating some salient portions of system300 configured to operate within a cloud computing environment 690. Inthe illustrative cloud computing environment, backup proxies and targetVM hosts are implemented as virtual machines. Thus, FIG. 6 depicts thesame components shown in FIG. 4, except that:

-   -   storage manager 340 is not shown in the present figure;    -   VSA 442, media agent 444, copies 315/316, and cache 404 are all        hosted by backup proxy VM 606, which is a virtual machine; and    -   target VM 333 and hypervisor 322-B are hosted by VM host B        601-B, which is a virtual machine, thus rendering the target VM        a nested VM running within host 601-B.        The same relationships described in earlier figures operate here        as well. The principal difference is that the backup proxy and        target VM hosts are virtualized. In some embodiments, the        multi-VM configuration of FIG. 5 is implemented in the present        virtualized environment as well.

VM host 601-B is a virtual machine that executes within cloud computingenvironment 690, and carries out the same functions as VM Host 301-B inregard to cross-hypervisor live-mount. VM host 601-B is served by ahypervisor (not shown here) and a virtual disk (not shown here) as iswell known in cloud computing.

Backup proxy 606 is a virtual machine that executes within cloudcomputing environment 690. Backup proxy carries out the same functionsas backup proxy machine 306 in regard to cross-hypervisor live-mount.Backup proxy 606 is served by a hypervisor (not shown here) and avirtual disk (not shown here) as is well known in cloud computing.

Cloud computing environment 690 is a cloud computing platform well knownin the art, and is supplied by one or more of a public cloud serviceprovider (e.g., Microsoft Azure, Amazon AWS, etc.), by a private cloudprovider, by a hybrid cloud provider, etc. without limitation.

FIG. 7 is a block diagram illustrating some salient portions of system300 configured to operate within a data storage management appliance790. Thus, FIG. 7 depicts the same components shown in FIG. 4, exceptthat:

-   -   storage manager 340 is not shown in the present figure;    -   VSA 442, media agent 444, copies 315/316, and cache 404 are all        hosted by appliance 790;    -   target VM 333 and target hypervisor 322-B are also hosted by        appliance 790, which operates target hypervisor 322-B as its own        native hypervisor, which can be used for purposes other than        cross-hypervisor live-mount; and    -   There are no distinct components for backup proxy and target VM        host.        The same relationships described in earlier figures operate here        as well. The principal difference is that the backup proxy and        target VM hosts operate within the same unified converged        appliance. In some embodiments, the multi-VM configuration of        FIG. 5 is implemented in the present appliance embodiment as        well.

Data storage management appliance 790 is a computing device comprisingone or more processors and computer memory for executing instructions,such as for executing VSA 442 and/or media agent 444 and/or hypervisor322-B. Appliance 790 also comprises mass data storage resources forstoring backup copies 315 and 316 and any number of other secondarycopies generated in system 300. Appliance 790 also comprises cache datastorage resources for storing cache 404 and any number of virtual disks412 therein. There is no limitation on how many appliances 790 can beimplemented in a system 300.

In regard to FIGS. 3-7, there is no limitation on combinations andpermutations thereof that can be implemented in a given embodimentaccording to the present invention. For example, a first plurality oftarget VMs 333 can be implemented via cloud computing as shown in FIG.6, a second plurality of target VMs 333 can be implemented via one ormore appliances 790, and additionally a third plurality of target VMs333 can be implemented in data center VM servers such as VM host 301-Bor in VM server clusters, or any combination thereof without limitation.This flexibility is made possible by the cross-hypervisor portabilitybuilt into the illustrative cross-hypervisor live-mount feature forbacked up VM data.

FIG. 8 depicts some salient operations of a method 800 according to anillustrative embodiment of the present invention. Method 800 isgenerally directed to setting up system 300 and a target VM forcross-hypervisor live-mount. Method 800 is performed by one or morecomponents of system 300, such as storage manager 340, VSA 442, andmedia agent 444, as described in more detail below.

At block 802, a request is received to live-mount a VM backup copy(e.g., 316) of a source VM (e.g., 302) to a target VM (e.g., 333). Therequest is from a user at a client computing device 102 or via an onlineconsole with access to system 300. Alternatively, the request is from asystem administrator who has access privileges and is using a consoleinto system 300. Illustratively, the request is received by storagemanager 340. Illustratively, storage manager 340 tracks the presence andstatus and other attributes of secondary copies in system 300 in itsmanagement database 146. Accordingly, storage manager 340 “is aware” ofwhen and how VM backup copy 316 was created. In alternative embodiments,the request is received by and block 802 is performed by VSA 442 and/ormedia agent 444. Control passes to block 804.

At block 804, if the requested VM backup copy 316 is suitable forcross-hypervisor live-mount, cache storage area 404 is created andexposed/exported as a mount point. Illustratively, storage manager 340determines whether backup copy 316 is suitable for cross-hypervisorlive-mount by determining whether copy 316 was generated as ahypervisor-free VM block-level copy. See, e.g., U.S. Pat. Pub. No.2017-0262204 A1, entitled “Hypervisor-Independent Block-Level LiveBrowse for Access to Backed up Virtual Machine (VM) Data andHypervisor-Free File-Level Recovery (Block-Level Pseudo-Mount)”, whichis incorporated by reference herein. If storage manager 340 determinesthat backup copy 316 is not suitable, a rejection message is transmittedto the requester.

If storage manager 340 determines that backup copy 316 is suitable forcross-hypervisor live-mount, storage manager 340 illustrativelydetermines a suitable VSA (e.g., 442) and a suitable media agent (e.g.,444) to assign to the live-mount operation. The determination is made atleast in part based on network topology of system 300 and/or resourceavailability relative to the target VM host 301-B and further relativeto the storage device that hosts VM backup copy 316 (this storage devicemay or may not be part of backup proxy 306 in some embodiments).Accordingly, storage manager 340 instructs VSA 442 and media agent 444that VM backup copy 316 is to be live-mounted using the illustrativecross-hypervisor live-mount feature.

Responsively, media agent 444 creates a local cache storage area, e.g.,404. The cache storage area 404 is closely associated with media agent444 and is implemented on the media agent's host, e.g., backup proxy306. This configuration promotes responsiveness to read requests issuedby target VMs 333. Media agent 444 exposes/exports cache storage area404 as a mount point (e.g., NFS export, iSCSI target, Fibre Channeltarget, without limitation) for target hypervisor 322-B. For example, inFIG. 4, the bi-directional arrow between target hypervisor 322-B andmedia agent 444 carries the NFS protocol. In some embodiments, a featureof media agent 444 named “Commvault 3DFS” exports cache storage area 404as an NFS share and mounts the share as an NFS mount point. Commvault3DFS is provided by Commvault Systems, Inc. of Tinton Falls, N.J., USA,but the invention is not so limited.

In some embodiments, target hypervisor 322-B is not compatible with NFSdata store, e.g., Hyper-V hypervisors from Microsoft Corp. Accordingly,iSCSI protocol is used to serve the cache storage area 404 to targethypervisor 322-B for the live-mounted VM 333. In such an embodiment, anillustrative pseudo-disk driver executes at backup proxy 306 and exposescache storage area 404 as an iSCSI target to target hypervisor 322-B.For example, in FIG. 4, the bi-directional arrow between targethypervisor 322-B and media agent 444 carries the iSCSI protocol. Anexample pseudo-disk driver is “Commvault CVBLK” from Commvault Systems,Inc., of Tinton Falls, N.J., USA, but the invention is not so limited.

The invention is not limited to NFS, iSCSI, 3DFS, and/or CVBLKimplementations. The particulars of which commands and operationalparameters to use for exposing/exporting storage resources such as cachestorage 404 depend on which cache storage technology and/or whichhypervisor are used in the embodiment. A person having ordinary skill inthe art, after reading the present disclosure, will know which commandsare suitable for mounting which kinds of technology, depending on theembodiment. Control passes to block 806.

At block 806, VSA 442 instructs target hypervisor 322-B to use theexported/exposed mount points as its native data store for configuringvirtual disks, which will be used by VMs executing over the hypervisor.Thus, cache storage 404 is where target hypervisor 322-B will configureand/or find virtual disks 412 for storing data used by VMs 333.

Configuration and/or feature parameters from source hypervisor 322-Awere backed up to metadata backup copy 315 by the hypervisor-independentblock-level backup operation that backed up source VM 302, and alsogenerated backup copy 316. (See, e.g., U.S. Pat. Pub. No. 2017-0262204A1, entitled “Hypervisor-Independent Block-Level Live Browse for Accessto Backed up Virtual Machine (VM) Data and Hypervisor-Free File-LevelRecovery (Block-Level Pseudo-Mount)”, which is incorporated by referenceherein). Optionally, some configuration and/or feature parameters thatare stored in metadata backup copy 315 are transmitted by media agent444 to target hypervisor 322-B for use thereby. This feature isoptional, because distinct source and target hypervisors likely do nothave compatible features, but in such embodiments where they do, mediaagent 444 taps metadata backup copy 315 for details and transmits themto the target hypervisor 322-B. Control passes to block 808.

At block 808, a virtual disk 412 is created within cache storage area404. Illustratively, target hypervisor 322-B creates the virtual disk,but in alternative embodiments media agent 444 does so and informstarget hypervisor 322-B accordingly. It should be noted that targethypervisor 322-B lacks any awareness or configuration about the factthat storage area 404 and virtual disks 412 within it are at least inpart under the control of media agent 444, rather than being under theexclusive control of hypervisor 322-B. Thus, target hypervisor 322-Btreats cache storage area 404 as raw storage suitable for creating andusing virtual disks 412 therein. Control passes to block 810.

At block 810, a target VM 333 is registered with target hypervisor322-B, thus creating an association between target VM 333 and virtualdisk 412 corresponding thereto and configured in cache storage area 404.In some embodiments, creating a VM 333, registering the VM with itshypervisor 322-B, and configuring the VM's corresponding virtual disk412 are all part of an integrated operation managed by a hypervisor suchas target hypervisor 322-B, thus incorporating block 808 into thepresent block 810. Illustratively, the registration is performed asinstructed by VSA 442 as part of the cross-hypervisor live-mountoperation, and in alternative embodiments, as instructed by media agent444. Control passes to block 812.

At block 812, virtual disk 412 becomes associated with the VM backupcopy 316 that was requested to be live-mounted. Illustratively, mediaagent 444 creates the association, which is illustratively stored atmedia agent 444. Control passes to block 814.

At block 814, the configuration steps for a given target VM 333 iscomplete for executing the illustrative cross-hypervisor live-mount ofVM backup copy 316. At this point, target VM 333 is ready to be poweredon for cross-hypervisor live-mount of VM backup copy 316 (see, e.g.,FIGS. 9-11). Control passes to block 816.

At block 816, control passes back to block 808 for performing theabove-recited operations for other target VMs (e.g., 333-N), thusenabling the illustrative cross-hypervisor live-mounting of the same VMbackup copy 316 for any number of other target VMs.

FIG. 9 depicts some salient operations of a method 900 according to anillustrative embodiment of the present invention. Method 900 isgenerally directed to executing cross-hypervisor live-mount in system300. Method 900 is performed by one or more components of system 300,such as media agent 444, as described in more detail below.

At block 902, a target VM 333 that was configured for cross-hypervisorlive-mount of VM backup copy 316 (see, e.g., FIG. 8) is powered up asconfigured and using corresponding virtual disk 412. The power-upoperation is performed by target hypervisor 322-B as is well known inthe art. Illustratively, VSA 442 and/or media agent 444, havingcompleted the configuration steps in method 800, instructs targethypervisor 322-B to power up the target VM 333. Control passes to block904.

At block 904, target VM 333 issues a read request for a data block. Theread request is received by target hypervisor 322-B. These operationsare well known in the art.

At block 906, target hypervisor 322-B directs the read request to thetarget VM's corresponding virtual disk 412. Again, this operation iswell known in the art.

At block 908, media agent 444 intercepts the read request directed tovirtual disk 412. This is made possible illustratively by a feature ofmedia agent 444 named “Commvault 3DFS” provided by Commvault SystemsInc. of Tinton Falls, N.J., USA. The invention is not limited to 3DFS.

At block 910, which is a decision point, media agent 444 determineswhether the requested data block is in the VM's virtual disk 412 in thecache storage area. A data block that was previously read by the giventarget VM 333 might be found in virtual disk 412. If found, controlpasses to block 914. Conversely, a block that has not been previouslyread and blocks that have been purged from virtual disk 412 are notfound in virtual disk 412 and therefore control passes to block 912.

At block 912, media agent 444 retrieves the data block from the VMbackup copy 316 that is associated with virtual disk 412. Media agent444 stores the data block to virtual disk 412 and control passes toblock 914.

At block 914, media agent 444 serves the pending read request fromvirtual disk 412 in cache storage area 404 to target hypervisor 322-B,which in turn transmits the data block to the requesting target VM 333.Control passes to block 1002 in FIG. 10.

FIG. 10 depicts some salient operations of a method 900 continued fromFIG. 9.

At block 1002, target VM 333 writes a data block, i.e., issues a writerequest. The write request comprising the data block is received bytarget hypervisor 322-B. These operations are well known in the art.

At block 1004, target hypervisor 322-B directs the write request to theVMs corresponding virtual disk 412 in cache storage area 404. Again,this operation is well known in the art.

At block 1006, media agent 444 intercepts the write request directed tovirtual disk 412, so that media agent 444 can keep track of the datablock as a written (“new”) data block. Media agent 444 keeps track ofdata blocks that are written to each virtual disk 412 in order toprevent such new data blocks from being purged from virtual disk 412while the corresponding target VM 333 is in operation. More details onhow media agent 444 manages the contents of virtual disks 412 are givenin FIG. 11 herein. Illustratively, media agent 444 uses one or moretracking maps (not shown here) for tracking new data blocks in thevirtual disks 412 in cache storage area 404. This is made possible bythe illustrative Commvault 3DFS feature of media agent 444, withoutlimitation.

At block 1008, the new data block is written to virtual disk 412 incache storage area 404. In some cases a previously read block isoverwritten by a new block. In some cases a previously written block isoverwritten by a newer new block. Since virtual disk 412 is the datarepository for target VM 333, it comprises current data. After a newdata block is written to virtual disk 412, control passes back to block904 for processing a VM read request or to block 1002 for processinganother VM write request.

FIG. 11 depicts some salient operations of a method 1100 according to anillustrative embodiment of the present invention. Method 1100 isgenerally directed to managing one or more virtual disks 412 in cachestorage area 404. Method 1100 is performed by one or more components ofsystem 300, such as media agent 444, as described in more detail below.

At block 1102, media agent 444 keeps track of new data blocks written bytarget VM 333 to its corresponding virtual disk 412 in cache storagearea 404. See also block 1006 in FIG. 10. Illustratively, media agent444 uses one or more tracking maps (not shown here) for tracking newdata blocks in the virtual disks 412 in cache storage area 404. This ismade possible by the illustrative Commvault 3DFS feature of media agent444, without limitation. The tracking of new data blocks continues solong as the given target VM 333 is in operation, i.e., until it ispowered down.

At block 1104, media agent 444 tracks the frequency of read requests foreach data block in virtual disk 412. Illustratively, media agent keeps alocal tracking map for the purpose. This is made possible by theillustrative Commvault 3DFS feature of media agent 444, withoutlimitation. The tracking of read frequency continues so long as thegiven target VM 333 is in operation, i.e., until it is powered down.

At block 1106, which is a decision point, media agent determines whethera given virtual disk 412 is running low on space, e.g., passed apre-defined storage threshold. One or more storage space thresholds forvirtual disks 412 are established when cache storage area 404 was firstconfigured at block 804. Alternatively, each virtual disk 412 receivesan individual storage space threshold that might vary among differentvirtual disks 412. For example and without limitation, each virtual diskmight be assigned 100 GB of storage space with a 75% threshold. At block1106, media agent determines whether a given virtual disk 412 has passedthe example storage threshold, e.g., 75%. If so, control passes to block1110. If not, control passes to block 1108.

At block 1108, media agent 444 continues processing read requests fromvirtual disk 412 and control passes back to block 1102 for processingfurther new block writes.

At block 1110, which is reached after media agent 444 determines atblock 1106 that a given virtual disk 412 passed its storage threshold,media agent 444 considers discarding the least recently used (LRU) datablocks from virtual disk 412 sufficient to fall back under the storagethreshold to pre-defined lower bound, e.g., 50% of storage space,without limitation. Accordingly, control passes to block 1112.

At block 1112, which is decision point, media agent 444 determineswhether the least recently used data block under consideration is a new(written) data block. If so, control passes to block 1116. Otherwise,i.e., the LRU data block is a data block previous read from VM backupcopy 316, control passes to block 1114.

At block 1114, which is a decision point, media agent 444 determineswhether the least recently used data block under consideration isfrequently read by the target VM. A frequency threshold is applied basedon frequency tracking at block 1104. For example and without limitation,a read frequency of 50 times/hour is treated as a threshold. At block1114, media agent 444 determines whether the least recently used datablock under consideration has been read more than the example frequencythreshold, e.g., 50 times/hour since the time it was added to virtualdisk 412. If not, i.e., it was less frequently read, control passes toblock 1118. Otherwise, i.e., the data block is frequently read, controlpasses to block 1116.

At block 1116, media agent 444 does not discard (purge) the leastrecently used data block under consideration, because it is a data blockfrequently read according to the pre-defined thresholds. Discarding sucha data block would be inefficient, as it is likely to be read again soonby the target VM and it would be brought back into virtual disk 412shortly. Control passes back to block 1110 to consider the next leastrecently read data block in virtual disk 412.

Although not expressly depicted here, media agent 444 is configured toexpand the size of any given virtual disk 412 to accommodate more andmore data blocks written by target VM 333. Likewise, media agent 444 isfurther configured to expand the size of any given virtual disk 412 toaccommodate more data blocks that are frequently read by the target VM333 so that churn can be reduced when reading data blocks from VM backupcopy 316.

At block 1118, which is reached when media agent determines that theleast recently used data block is not a new data block and notfrequently read, media agent 444 discards (purges) the data block fromvirtual disk 412. This frees up storage space. Control passes back toblock 1106.

In regard to the figures described herein, other embodiments arepossible within the scope of the present invention, such that theabove-recited features, components, steps, blocks, operations, messages,requests, queries, and/or instructions are differently arranged,sequenced, sub-divided, organized, and/or combined. In some embodiments,a different component may initiate or execute a given operation. Forexample, in some embodiments, operations recited here as being performedby media agent 444 are performed by VSA 442. In other embodiments,operations recited here as being performed by VSA 442 are performed bymedia agent 444. In yet other embodiments, operations recited here asbeing performed by media agent 444 are consolidated into a separatefunctional component of system 300 that is not part of media agent 444.

Although not expressly depicted in the present figures, a virtual disk412 is discarded when its corresponding target VM 333 is powered down,but the invention is not so limited. In alternative embodiments, datablocks written by target VM 333 to its corresponding virtual disk 412are not discarded and instead are persisted for future use, e.g.,integrated into VM backup copy 316; associated with VM backup copy 316;placed into a new backup copy that integrates backup copy 316 with thewritten data blocks; etc., without limitation. For example, in someembodiments, data blocks written by target VM 333 to its virtual disk412 are saved as an incremental backup copy associated with VM backupcopy 316 and the incremental backup copy is used by another target VM333 at another place and time; and/or by the original source VM 302 in afailback scenario. Thus, in a failback scenario, data generated by atarget VM 333 is not lost and is made portable back to and usable by theoriginal source VM 302. Lifecycle management policies govern thelongevity of such example incremental backup copies. In someembodiments, VM service is sped up at any new target VM 333 and/orsource VM 302 by pre-populating the written data blocks into the newvirtual disk, thus making the written data blocks immediately availableon VM power-up.

Although not expressly depicted in the present figures, media agent 444is further configured to adjust the size of cache storage area 404and/or of individual virtual disks 412 responsive to other storage needsat backup proxy 306. For example, if additional VM backup copies 316need to be stored at backup proxy 306, media agent 444 is configured tomake cache storage area 404 smaller, which includes more frequentpurging of least-used data blocks from the virtual disks 412.Conversely, if more storage space becomes available, media agent 444 isconfigured to expand cache storage area 444 so that purging least-useddata blocks from virtual disks 412 occurs less frequently.

Example Embodiments

Some example enumerated embodiments of the present invention are recitedin this section in the form of methods, systems, and non-transitorycomputer-readable media, without limitation.

According to an example embodiment of the present invention, a methodcomprises: powering on a first virtual machine on a first hypervisor,wherein a first virtual disk is configured to store data for the firstvirtual machine, wherein the first virtual disk is associated with abackup copy of a second virtual machine, wherein the backup copy wasgenerated in a hypervisor-independent format by a block-level backupoperation of a second virtual disk of the second virtual machine,wherein the first virtual disk is configured in cache storage that ismounted to the first hypervisor, and wherein the first hypervisorexecutes on a first computing device comprising one or more processorsand computer memory; by the first hypervisor, transmitting to the firstvirtual disk a first read request issued by the first virtual machinefor a first data block; by a media agent that maintains the cachestorage, intercepting the first read request transmitted to the firstvirtual disk, wherein the media agent executes on a second computingdevice comprising the cache storage, one or more processors, andcomputer memory; based on determining by the media agent that the firstdata block is not in the first virtual disk, by the media agent: (i)reading the first data block from the backup copy, and (ii) storing thefirst data block to the first virtual disk; and based on determining bythe media agent that first data block is in the first virtual disk,serving the first data block from the first virtual disk to the firsthypervisor, thereby providing the first data block from the backup copyof the second virtual machine to the first virtual machine. Theabove-recited method wherein by using the first data block the firstvirtual machine uses backed up data from the second virtual machine,which executed over a second hypervisor of a different type from thefirst hypervisor. The above-recited method wherein the second virtualmachine executed over a second hypervisor of a different type from thefirst hypervisor, and wherein by using the first data block the firstvirtual machine uses backed up data from the second virtual machinewithout metadata from the second hypervisor being converted for thefirst hypervisor. The above-recited method wherein by using the firstdata block the first virtual machine uses backed up data from the secondvirtual machine, which executed over a second hypervisor of a differenttype from the first hypervisor, wherein metadata from the secondhypervisor was not included in the backup copy by the block-level backupoperation, and wherein the first virtual machine uses backed up datafrom the second virtual machine without the metadata from the secondhypervisor being converted for the first hypervisor. The above-recitedmethod further comprises: by the first hypervisor, transmitting to thefirst virtual disk a first write request for a second data block issuedby the first virtual machine; by the media agent, intercepting the firstwrite request transmitted to the first virtual disk; by the media agent,storing the second data block to the first virtual disk; and by themedia agent, keeping track of the second data block to prevent thesecond data block from being discarded from the first virtual disk whilethe first virtual machine executes on the first hypervisor. Theabove-recited method further comprises: based on determining by themedia agent that the second data block is in the first virtual disk,serving the second data block from the first virtual disk to the firsthypervisor in response to a second read request issued by the firstvirtual machine, thereby providing the second data block generated bythe first virtual machine from the cache storage. The above-recitedmethod further comprising: before the first virtual machine is poweredup: by the media agent, exporting the cache storage as a mount point tothe first hypervisor, thereby providing native Network File System (NFS)data storage to the first hypervisor for one or more virtual machinesthat are to execute over the first hypervisor, including the firstvirtual machine. The above-recited method further comprising: before thefirst virtual machine is powered up: by the media agent, exposing thecache storage as an Internet Small Computer Systems Interface (iSCSI)target to the first hypervisor, thereby providing native block-leveldata storage to the first hypervisor for one or more virtual machinesthat are to execute over the first hypervisor, including the firstvirtual machine.

The above-recited method further comprises: based on determining by themedia agent that storage space in the first virtual disk is below apredefined threshold, identifying by the media agent a second data blockin the first virtual disk that is least recently used by the firstvirtual machine; and based on determining by the media agent that thesecond data block was written by the first virtual machine, declining todiscard the second data block from the first virtual disk. Theabove-recited method further comprises: based on determining by themedia agent that storage space in the first virtual disk is below apredefined threshold, identifying by the media a second data block inthe first virtual disk that is least recently used by the first virtualmachine; based on determining by the media agent that the second datablock: (i) was not written by the first virtual machine and (ii) hasbeen read by the first virtual machine more often than a predefinedthreshold, declining to discard the second data block from the firstvirtual disk. The above-recited method further comprises: based ondetermining by the media agent that storage space in the first virtualdisk is below a predefined threshold, identifying by the media agent asecond data block in the first virtual disk that is least recently usedby the first virtual machine; based on determining by the media agentthat the second data block: (i) was not written by the first virtualmachine and (ii) has been read by the first virtual machine less oftenthan a predefined threshold, discarding the second data block from thefirst virtual disk, thereby freeing up storage space in the firstvirtual disk.

The above-recited method further comprises: before the first virtualmachine is powered up: by the media agent, exporting the cache storageas a mount point to the first hypervisor, thereby providing native datastorage to the first hypervisor for one or more virtual machines thatare to execute over the first hypervisor, including the first virtualmachine. The above-recited method further comprises: before the firstvirtual machine is powered up: by the media agent, exposing the cachestorage as a mount point to the first hypervisor, thereby providingnative data storage to the first hypervisor for one or more virtualmachines that are to execute over the first hypervisor, including thefirst virtual machine. The above-recited method wherein the backup copyof the second virtual machine is live-mounted to the first virtualmachine without metadata from a second hypervisor used by the secondvirtual machine being converted for the first hypervisor, which is of adifferent type from the second hypervisor. The above-recited methodwherein the backup copy of the second virtual machine is live-mounted tothe first virtual machine without metadata from a second hypervisor usedby the second virtual machine being converted for the first hypervisor,which is of a different type from the second hypervisor, and furtherwithout restoring the backup copy of the second virtual machine in itsentirety to the first virtual disk. The above-recited method whereinwithout restoring the backup copy of the second virtual machine in itsentirety to the virtual disk, the first virtual machine executes overthe first hypervisor by using data blocks from the backup copy of thesecond virtual machine. The above-recited method wherein the media agentcauses the powering up of the first virtual machine on the firsthypervisor after associating the first virtual disk with the backup copyof the second virtual machine. The above-recited method wherein a dataagent that also executes on the second computing device causes thepowering up of the first virtual machine on the first hypervisor afterthe media agent associates the first virtual disk with the backup copyof the second virtual machine.

According to another example embodiment, a system comprises: a firstcomputing device comprising one or more processors and computer memory,wherein a first hypervisor executes thereon; a second computing devicein communication with the first computing device, wherein the secondcomputing device comprises one or more processors and computer memoryand further comprises cache storage; a backup copy of a second virtualmachine that executed over a second hypervisor of a different type fromthe first hypervisor, wherein the backup copy was generated in ahypervisor-independent format by a block-level backup operation of asecond virtual disk of the second virtual machine; and wherein thesecond computing device is configured to: cause the cache storage to bemounted to the first hypervisor as native storage for one or morevirtual machines that will execute over the first hypervisor, includinga first virtual machine, configure within the cache storage a firstvirtual disk for storing data for the first virtual machine, associatethe backup copy of the second virtual machine with the first virtualdisk, intercept from the first hypervisor a first read request issued bythe first virtual machine for a first data block to be obtained from thefirst virtual disk, based on determining that the first data block isnot in the first virtual disk: (i) read the first data block from thebackup copy, and (ii) store the first data block to the first virtualdisk, and based on determining that the first data block is in the firstvirtual disk, serve the first data block from the first virtual disk tothe first hypervisor. The above-recited system thereby provides thefirst data block to the first virtual machine on the first hypervisorfrom the backup copy of the second virtual machine, which used thesecond hypervisor of the different type from the first hypervisor. Theabove-recited system wherein a media agent that executes on the secondcomputing device performs the configure, associate, intercept, anddetermining operations at the second computing device. The above-recitedsystem wherein at least one of a data agent and a media agent thatexecute on the second computing device performs the operations at thesecond computing device.

According to yet another embodiment, a system comprises: a firstcomputing device comprising one or more processors and computer memory,wherein a first hypervisor executes thereon; a second computing devicein communication with the first computing device, wherein a media agentin communication with the first hypervisor executes on the secondcomputing device, and wherein the second computing device comprises oneor more processors and computer memory and further comprises cachestorage maintained by the media agent; a backup copy of a second virtualmachine that executed over a second hypervisor, wherein the backup copywas generated in a hypervisor-independent format by a block-level backupoperation of a second virtual disk of the second virtual machine;wherein the second computing device is configured to: by the mediaagent, cause the cache storage to be mounted to the first hypervisor,thereby providing native data storage to the first hypervisor for one ormore virtual machines to execute over the first hypervisor, including afirst virtual machine, by the media agent, configure within the cachestorage a first virtual disk for storing data for the first virtualmachine, by the media agent, associate the backup copy of the secondvirtual machine with the first virtual disk, by the media agent,intercepting from the first hypervisor a first read request issued bythe first virtual machine for a first data block to be read from thefirst virtual disk, based on determining by the media agent that thefirst data block is not in the first virtual disk, by the media agent:(i) reading the first data block from the backup copy, and (ii) storingthe first data block to the first virtual disk, based on determining bythe media agent that first data block is in the first virtual disk,serving the first data block from the first virtual disk to the firsthypervisor, thereby providing the first data block from the backup copyof the second virtual machine to the first virtual machine to use. Theabove-recited system wherein before the first virtual machine is poweredup the media agent exposes the cache storage as a mount point to thefirst hypervisor, thereby providing native data storage to the firsthypervisor for one or more virtual machines that are to execute over thefirst hypervisor, including the first virtual machine.

According to still another example embodiment, a non-transitorycomputer-readable medium that, when executed by a second computingdevice comprising one or more processors and computer memory, causes thesecond computing device to: cause cache storage configured at the secondcomputing device to be mounted to a first hypervisor as native storagefor one or more virtual machines that will execute over the firsthypervisor, including a first virtual machine, wherein the firsthypervisor executes on one of: (i) the second computing device and (ii)a first computing device distinct from the second computing device andcomprising one or more processors and computer memory; configure withinthe cache storage a first virtual disk for storing data for the firstvirtual machine; associate a backup copy of a second virtual machinewith the first virtual disk, wherein the backup copy was generated in ahypervisor-independent format by a block-level backup operation of asecond virtual disk of the second virtual machine; intercept from thefirst hypervisor a first read request issued by the first virtualmachine for a first data block to be obtained from the first virtualdisk; based on determining that the first data block is not in the firstvirtual disk: (i) read the first data block from the backup copy, and(ii) store the first data block to the first virtual disk; and based ondetermining that the first data block is in the first virtual disk,serve the first data block from the first virtual disk to the firsthypervisor. The above-recited computer-readable medium thereby providesthe first data block to the first virtual machine on the firsthypervisor from the backup copy of the second virtual machine, whichused a second hypervisor of a different type from the first hypervisor.

The above-recited computer-readable medium wherein a virtual disk isdiscarded when its corresponding target VM is powered down. Theabove-recited computer-readable medium wherein data blocks written bytarget VM to its virtual disk are not discarded and instead arepersisted for future use, such as integrated into VM backup copy,associated with VM backup copy, placed into a new backup copy thatintegrates backup copy with the written data blocks. The above-recitedcomputer-readable medium wherein data blocks written by target VM to itscorresponding virtual disk are saved as an incremental backup copyassociated with VM backup copy and the incremental backup copy is usedby another target VM at another place and time. The above-recitedcomputer-readable medium wherein data blocks written by target VM to itscorresponding virtual disk are saved as an incremental backup copyassociated with VM backup copy and the incremental backup copy is usedby the original source VM in a failback scenario. The above-recitedcomputer-readable medium wherein in a failback scenario, data generatedby a target VM is made portable back to the original source VM. Theabove-recited computer-readable medium wherein lifecycle managementpolicies govern the longevity of incremental backup copies. Theabove-recited computer-readable medium wherein VM service is sped up atany new target VM and/or source VM by pre-populating the written datablocks into a new virtual disk, thus making the written data blockimmediately available on VM power-up.

According to an illustrative example of the present invention, a methodcomprises: by a first hypervisor, transmitting to a first virtual disk afirst write request for a first data block issued by a first virtualmachine that executes on the first hypervisor; wherein the firsthypervisor executes on a first computing device comprising one or moreprocessors and computer memory, wherein the first virtual disk isconfigured to store data for the first virtual machine, wherein thefirst virtual disk is associated with a backup copy of a second virtualmachine, wherein the backup copy was generated in ahypervisor-independent format by a block-level backup operation of asecond virtual disk of the second virtual machine, and wherein the firstvirtual disk is configured in cache storage that is mounted to the firsthypervisor as native data storage for virtual machines that are toexecute thereupon, including the first virtual machine; by a media agentthat maintains the cache storage, intercepting the first write requesttransmitted to the first virtual disk, wherein the media agent executeson a second computing device comprising the cache storage, one or moreprocessors, and computer memory; by the media agent, storing the firstdata block to the first virtual disk; based on determining by the mediaagent that storage space in the first virtual disk is below a predefinedthreshold, identifying by the media agent the first data block as beingleast recently used in the first virtual disk; and based on determiningby the media agent that the first data block was written by the firstvirtual machine, declining to discard the first data block from thefirst virtual disk. The above-recited method wherein the media agentkeeps track of data blocks written to the first virtual disk resultingfrom write requests issued by the first virtual machine, including thefirst data block. The above-recited method wherein the determining bythe media agent that the first data block was written by the firstvirtual machine is based on the media agent keeping track of data blockswritten to the first virtual disk resulting from write requests issuedby the first virtual machine, including the first data block. Theabove-recited method further comprises: based on determining by themedia agent that the first data block is in the first virtual disk,serving the first data block from the first virtual disk to the firsthypervisor in response to a second read request issued by the firstvirtual machine, thereby providing the first data block generated by thefirst virtual machine from the cache storage.

The above-recited method further comprises: based on the media agentdeclining to discard the first data block from the first virtual disk,identifying by the media agent in the first virtual disk a second datablock that is least recently used by the first virtual machine; andbased on determining by the media agent that the second data block wasnot written by the first virtual machine and has been read from thebackup copy of the second virtual machine that is associated with thefirst virtual disk, discarding the second data block from the firstvirtual disk, thereby saving storage space allocated to the firstvirtual disk in the cache storage. The above-recited method furthercomprises: based on determining by the media agent that storage space inthe first virtual disk is below a predefined threshold, identifying bythe media agent in the first virtual disk a second data block that isleast recently used by the first virtual machine; and based ondetermining by the media agent that the second data block was notwritten by the first virtual machine and has been read by the firstvirtual machine more often than a predefined threshold, declining todiscard the second data block from the first virtual disk in the cachestorage. The above-recited method further comprises: based ondetermining by the media agent that storage space in the first virtualdisk is below a predefined threshold, identifying by the media agent inthe first virtual disk a second data block that is least recently usedby the first virtual machine; and based on determining by the mediaagent that the second data block was not written by the first virtualmachine and has been read by the first virtual machine less often than apredefined threshold, discarding the second data block from the firstvirtual disk in the cache storage. The above-recited method wherein thecache storage comprises a plurality of virtual disks, each onecorresponding to a respective virtual machine that executes on the firsthypervisor; and wherein each virtual disk in the plurality of virtualdisks is associated with the backup copy of the second virtual machine,thereby enabling each respective virtual machine to use data blocks fromthe backup copy of the second virtual machine. The above-recited methodwherein the cache storage comprises a plurality of virtual disks, eachone corresponding to a respective virtual machine that executes on thefirst hypervisor; and wherein each virtual disk in the plurality ofvirtual disks is associated with the backup copy of the second virtualmachine. The above-recited method thereby enables each respectivevirtual machine to use data blocks from the backup copy of the secondvirtual machine independently of which data blocks from the backup copyare used by other respective virtual machines that execute on the firsthypervisor. The above-recited method further comprises: by the firsthypervisor, transmitting to the first virtual disk a first read requestissued by the first virtual machine for a second data block; by themedia agent, intercepting the first read request transmitted to thefirst virtual disk, based on determining by the media agent that thesecond data block is not in the first virtual disk, by the media agent:(i) reading the second data block from the backup copy, and (ii) storingthe second data block to the first virtual disk; and based ondetermining by the media agent that the second data block is in thefirst virtual disk, serving the second data block from the first virtualdisk to the first hypervisor, thereby providing the second data blockfrom the backup copy of the second virtual machine to the first virtualmachine. 7. The above-recited method further comprising: before thefirst virtual machine is powered up: by the media agent, exporting thecache storage as a mount point to the first hypervisor, therebyproviding native Network File System (NFS) data storage to the firsthypervisor for one or more virtual machines that are to execute over thefirst hypervisor, including the first virtual machine. The above-recitedmethod further comprising: before the first virtual machine is poweredup: by the media agent, exposing the cache storage as an Internet SmallComputer Systems Interface (iSCSI) target to the first hypervisor,thereby providing native block-level data storage to the firsthypervisor for one or more virtual machines that are to execute over thefirst hypervisor, including the first virtual machine. The above-recitedmethod wherein the cache storage is an exported Network File System(NFS). The above-recited method wherein the cache storage is exposed asan Internet Small Computer Systems Interface (iSCSI) target to the firsthypervisor.

According to another illustrative embodiment, a method comprises:powering on a first virtual machine on a first hypervisor, wherein afirst virtual disk is configured to store data for the first virtualmachine, wherein the first virtual disk is associated with a backup copyof a second virtual machine, wherein the backup copy was generated in ahypervisor-independent format by a block-level backup operation of asecond virtual disk of the second virtual machine, wherein the firstvirtual disk is configured in cache storage mounted to the firsthypervisor before the first virtual machine was powered on, wherein thefirst hypervisor executes on a first computing device comprising one ormore processors and computer memory; by the first hypervisor,transmitting to the first virtual disk a first write request issued bythe first virtual machine for a first data block; by a media agent thatmaintains the cache storage, intercepting the first write requesttransmitted to the first virtual disk, wherein the media agent executeson a second computing device comprising the cache storage, one or moreprocessors, and computer memory; by the media agent, storing the firstdata block to the first virtual disk; by the media agent, keeping trackof data blocks being written to the first virtual disk resulting fromwrite requests issued by the first virtual machine; based on determiningby the media agent that storage space in the first virtual disk is belowa predefined threshold, identifying by the media agent the first datablock as being a least-recently-used data block in the first virtualdisk. The above-recited method further comprises: based on determiningby the media agent that the first data block resulted from a writerequest issued by the first virtual machine, declining to discard thefirst data block from the first virtual disk. The above-recited methodfurther comprises: based on determining by the media agent that a seconddata block in the first virtual disk resulted from a read request issuedby the first virtual machine, discarding the second data block from thefirst virtual disk. The above-recited method further comprises: based ondetermining by the media agent that the first data block is in the firstvirtual disk, serving the first data block from the first virtual diskto the first hypervisor in response to a second read request issued bythe first virtual machine, thereby providing the first data blockgenerated by the first virtual machine from the cache storage. Theabove-recited method further comprises: based on the media agentdeclining to discard the first data block from the first virtual disk,identifying by the media agent in the first virtual disk a second datablock that is least recently used by the first virtual machine. Theabove-recited method further comprises: based on determining by themedia agent that the second data block was not written by the firstvirtual machine and has been read from the backup copy of the secondvirtual machine that is associated with the first virtual disk,discarding the second data block from the first virtual disk, therebysaving storage space allocated to the first virtual disk in the cachestorage. The above-recited method further comprises: based ondetermining by the media agent that storage space in the first virtualdisk is below a predefined threshold, identifying by the media agent inthe first virtual disk a second data block that is least recently usedby the first virtual machine; and based on determining by the mediaagent that the second data block was not written by the first virtualmachine and has been read by the first virtual machine more often than apredefined threshold, declining to discard the second data block fromthe first virtual disk in the cache storage. The above-recited methodfurther comprises: based on determining by the media agent that storagespace in the first virtual disk is below a predefined threshold,identifying by the media agent in the first virtual disk a second datablock that is least recently used by the first virtual machine; andbased on determining by the media agent that the second data block wasnot written by the first virtual machine and has been read by the firstvirtual machine less often than a predefined threshold, discarding thesecond data block from the first virtual disk in the cache storage.

The above-recited method wherein the cache storage comprises a pluralityof virtual disks, each one corresponding to a respective virtual machinethat executes on the first hypervisor; and wherein each virtual disk inthe plurality of virtual disks is associated with the backup copy of thesecond virtual machine, thereby enabling each respective virtual machineto use data blocks from the backup copy of the second virtual machine.The above-recited method wherein the cache storage comprises a pluralityof virtual disks, each one corresponding to a respective virtual machinethat executes on the first hypervisor; and wherein each virtual disk inthe plurality of virtual disks is associated with the backup copy of thesecond virtual machine. The above-recited method thereby enables eachrespective virtual machine to use data blocks from the backup copy ofthe second virtual machine independently of which data blocks from thebackup copy are used by other respective virtual machines that executeon the first hypervisor.

According to yet another illustrative embodiment, a data storagemanagement system comprises: a first computing device that executes afirst hypervisor which executes one or more virtual machines including afirst virtual machine, wherein the first computing device comprises oneor more processors and computer memory; a second computing device incommunication with the first computing device; wherein the firsthypervisor is configured to transmit to a first virtual disk a firstwrite request for a first data block issued by the first virtual machinethat executes on the first hypervisor; wherein the second computingdevice comprises cache storage comprising the first virtual disk, whichis configured to store data for the first virtual machine, wherein thefirst virtual disk is associated with a backup copy of a second virtualmachine, wherein the backup copy was generated in ahypervisor-independent format by a block-level backup operation of asecond virtual disk of the second virtual machine, and wherein the cachestorage is mounted to the first hypervisor as native data storage forthe one or more virtual machines. The above-recited data storagemanagement system further comprises: wherein the second computing deviceis configured to: intercept the first write request transmitted to thefirst virtual disk, store the first data block to the first virtualdisk, based on determining that storage space in the first virtual diskis below a predefined threshold, identify the first data block as beingleast recently used in the first virtual disk, and based on determiningthat the first data block was written by the first virtual machine,declining to discard the first data block from the first virtual disk.The above-recited data storage management system wherein the secondcomputing device is further configured to: based on determining that asecond data block in the first virtual disk resulted from a read requestissued by the first virtual machine, discarding the second data blockfrom the first virtual disk. The above-recited data storage managementsystem wherein the second computing device and/or media agent executingthereon is further configured to adjust the size of cache storage areaand/or of individual virtual disks responsive to other storage needs atthe second computing device. The above-recited data storage managementsystem wherein the second computing device and/or media agent executingthereon is further configured to: if additional VM backup copies need tobe stored at the second computing device, making the cache storage areasmaller, thereby causing more frequent purging of least-used data blocksfrom the virtual disk. The above-recited data storage management systemwherein the second computing device and/or media agent executing thereonis further configured to: if more storage space becomes available at thesecond computing device, expanding the cache storage area so thatpurging least-used data blocks from virtual disks is less frequent.

In other embodiments, a system or systems may operate according to oneor more of the methods and/or computer-readable media recited in thepreceding paragraphs. In yet other embodiments, a method or methods mayoperate according to one or more of the systems and/or computer-readablemedia recited in the preceding paragraphs. In yet more embodiments, acomputer-readable medium or media, excluding transitory propagatingsignals, may cause one or more computing devices having one or moreprocessors and non-transitory computer-readable memory to operateaccording to one or more of the systems and/or methods recited in thepreceding paragraphs.

Terminology

Conditional language, such as, among others, “can,” “could,” “might,” or“may,” unless specifically stated otherwise, or otherwise understoodwithin the context as used, is generally intended to convey that certainembodiments include, while other embodiments do not include, certainfeatures, elements and/or steps. Thus, such conditional language is notgenerally intended to imply that features, elements and/or steps are inany way required for one or more embodiments or that one or moreembodiments necessarily include logic for deciding, with or without userinput or prompting, whether these features, elements and/or steps areincluded or are to be performed in any particular embodiment.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense, i.e., in the sense of “including, but notlimited to.” As used herein, the terms “connected,” “coupled,” or anyvariant thereof means any connection or coupling, either direct orindirect, between two or more elements; the coupling or connectionbetween the elements can be physical, logical, or a combination thereof.Additionally, the words “herein,” “above,” “below,” and words of similarimport, when used in this application, refer to this application as awhole and not to any particular portions of this application. Where thecontext permits, words using the singular or plural number may alsoinclude the plural or singular number respectively. The word “or” inreference to a list of two or more items, covers all of the followinginterpretations of the word: any one of the items in the list, all ofthe items in the list, and any combination of the items in the list.Likewise the term “and/or” in reference to a list of two or more items,covers all of the following interpretations of the word: any one of theitems in the list, all of the items in the list, and any combination ofthe items in the list.

In some embodiments, certain operations, acts, events, or functions ofany of the algorithms described herein can be performed in a differentsequence, can be added, merged, or left out altogether (e.g., not allare necessary for the practice of the algorithms). In certainembodiments, operations, acts, functions, or events can be performedconcurrently, e.g., through multi-threaded processing, interruptprocessing, or multiple processors or processor cores or on otherparallel architectures, rather than sequentially.

Systems and modules described herein may comprise software, firmware,hardware, or any combination(s) of software, firmware, or hardwaresuitable for the purposes described. Software and other modules mayreside and execute on servers, workstations, personal computers,computerized tablets, PDAs, and other computing devices suitable for thepurposes described herein. Software and other modules may be accessiblevia local computer memory, via a network, via a browser, or via othermeans suitable for the purposes described herein. Data structuresdescribed herein may comprise computer files, variables, programmingarrays, programming structures, or any electronic information storageschemes or methods, or any combinations thereof, suitable for thepurposes described herein. User interface elements described herein maycomprise elements from graphical user interfaces, interactive voiceresponse, command line interfaces, and other suitable interfaces.

Further, processing of the various components of the illustrated systemscan be distributed across multiple machines, networks, and othercomputing resources. Two or more components of a system can be combinedinto fewer components. Various components of the illustrated systems canbe implemented in one or more virtual machines, rather than in dedicatedcomputer hardware systems and/or computing devices. Likewise, the datarepositories shown can represent physical and/or logical data storage,including, e.g., storage area networks or other distributed storagesystems. Moreover, in some embodiments the connections between thecomponents shown represent possible paths of data flow, rather thanactual connections between hardware. While some examples of possibleconnections are shown, any of the subset of the components shown cancommunicate with any other subset of components in variousimplementations.

Embodiments are also described above with reference to flow chartillustrations and/or block diagrams of methods, apparatus (systems) andcomputer program products. Each block of the flow chart illustrationsand/or block diagrams, and combinations of blocks in the flow chartillustrations and/or block diagrams, may be implemented by computerprogram instructions. Such instructions may be provided to a processorof a general purpose computer, special purpose computer,specially-equipped computer (e.g., comprising a high-performancedatabase server, a graphics subsystem, etc.) or other programmable dataprocessing apparatus to produce a machine, such that the instructions,which execute via the processor(s) of the computer or other programmabledata processing apparatus, create means for implementing the actsspecified in the flow chart and/or block diagram block or blocks. Thesecomputer program instructions may also be stored in a non-transitorycomputer-readable memory that can direct a computer or otherprogrammable data processing apparatus to operate in a particularmanner, such that the instructions stored in the computer-readablememory produce an article of manufacture including instruction meanswhich implement the acts specified in the flow chart and/or blockdiagram block or blocks. The computer program instructions may also beloaded to a computing device or other programmable data processingapparatus to cause operations to be performed on the computing device orother programmable apparatus to produce a computer implemented processsuch that the instructions which execute on the computing device orother programmable apparatus provide steps for implementing the actsspecified in the flow chart and/or block diagram block or blocks.

Any patents and applications and other references noted above, includingany that may be listed in accompanying filing papers, are incorporatedherein by reference. Aspects of the invention can be modified, ifnecessary, to employ the systems, functions, and concepts of the variousreferences described above to provide yet further implementations of theinvention. These and other changes can be made to the invention in lightof the above Detailed Description. While the above description describescertain examples of the invention, and describes the best modecontemplated, no matter how detailed the above appears in text, theinvention can be practiced in many ways. Details of the system may varyconsiderably in its specific implementation, while still beingencompassed by the invention disclosed herein. As noted above,particular terminology used when describing certain features or aspectsof the invention should not be taken to imply that the terminology isbeing redefined herein to be restricted to any specific characteristics,features, or aspects of the invention with which that terminology isassociated. In general, the terms used in the following claims shouldnot be construed to limit the invention to the specific examplesdisclosed in the specification, unless the above Detailed Descriptionsection explicitly defines such terms. Accordingly, the actual scope ofthe invention encompasses not only the disclosed examples, but also allequivalent ways of practicing or implementing the invention under theclaims.

To reduce the number of claims, certain aspects of the invention arepresented below in certain claim forms, but the applicant contemplatesother aspects of the invention in any number of claim forms. Forexample, while only one aspect of the invention is recited as ameans-plus-function claim under 35 U.S.C. sec. 112(f) (AIA), otheraspects may likewise be embodied as a means-plus-function claim, or inother forms, such as being embodied in a computer-readable medium. Anyclaims intended to be treated under 35 U.S.C. § 112(f) will begin withthe words “means for,” but use of the term “for” in any other context isnot intended to invoke treatment under 35 U.S.C. § 112(f). Accordingly,the applicant reserves the right to pursue additional claims afterfiling this application, in either this application or in a continuingapplication.

What is claimed is:
 1. A computer-implemented method comprising:powering up a first virtual machine on a first hypervisor, wherein afirst virtual disk is configured to store data for the first virtualmachine, wherein the first virtual disk is associated with a block-levelbackup copy of a second virtual machine on a second hypervisor, whereinmetadata from the second hypervisor was not included in the block-levelbackup copy of the second virtual machine, wherein the first virtualdisk is configured in cache storage that is mounted to the firsthypervisor, and wherein the first hypervisor executes on a firstcomputing device comprising one or more hardware processors; by thefirst hypervisor, transmitting to the first virtual disk a first readrequest issued by the first virtual machine for a first data block; by amedia agent, intercepting the first read request, wherein the mediaagent executes on a second computing device comprising the cache storageand one or more hardware processors; based on determining by the mediaagent that the first data block is not in the first virtual disk, by themedia agent: (i) reading the first data block from the block-levelbackup copy, and (ii) storing the first data block to the first virtualdisk, and serving the first data block from the first virtual disk tothe first hypervisor in response to the first read request.
 2. Themethod of claim 1, wherein the second hypervisor is one of: a same typeas the first hypervisor, and a different type as the first hypervisor.3. The method of claim 1, wherein the first virtual machine executing onthe first hypervisor obtains backed up data from the block-level backupcopy of the second virtual machine of the second hypervisor, includingthe first data block, without conversion of the metadata from the secondhypervisor, which was not included in the block-level backup copy. 4.The method of claim 1, further comprising: by the first hypervisor,transmitting to the first virtual disk a first write request comprisinga second data block issued by the first virtual machine; by the mediaagent, intercepting the first write request; by the media agent, storingthe second data block to the first virtual disk; and by the media agent,serving the second data block from the first virtual disk to the firsthypervisor in response to a second read request issued by the firstvirtual machine.
 5. The method of claim 4 further comprising: by themedia agent, preventing the second data block from being discarded fromthe first virtual disk while the first virtual machine executes on thefirst hypervisor.
 6. The method of claim 1, further comprising: beforethe first virtual machine is powered up: by the media agent, exportingthe cache storage as a Network File System (NFS) mount point to thefirst hypervisor.
 7. The method of claim 1, further comprising: beforethe first virtual machine is powered up: by the media agent, exposingthe cache storage as an Internet Small Computer Systems Interface(iSCSI) target to the first hypervisor.
 8. The method of claim 1,wherein the first virtual machine executing on the first hypervisor usesdata blocks from the block-level backup copy of the second virtualmachine without restoring the block-level backup copy in its entirety.9. The method of claim 1, wherein the media agent causes the powering upof the first virtual machine on the first hypervisor after associatingthe first virtual disk with the block-level backup copy of the secondvirtual machine.
 10. The method of claim 1, wherein a data agent thatalso executes on the second computing device causes the powering up ofthe first virtual machine on the first hypervisor after the media agentassociates the first virtual disk with the block-level backup copy ofthe second virtual machine.
 11. A computer-implemented methodcomprising: powering up a first virtual machine on a first hypervisor,wherein a first virtual disk is configured to store data for the firstvirtual machine, wherein the first virtual disk is associated with ablock-level backup copy of a second virtual machine on a secondhypervisor, wherein metadata from the second hypervisor was not includedin the block-level backup copy of the second virtual machine, whereinthe first virtual disk is configured in cache storage that is mounted tothe first hypervisor, and wherein the first hypervisor executes on afirst computing device comprising one or more hardware processors; bythe first hypervisor, transmitting to the first virtual disk a firstwrite request comprising a first data block issued by the first virtualmachine; by a media agent, intercepting the first write request, whereinthe media agent executes on a second computing device comprising thecache storage and one or more hardware processors; by the media agent,storing the first data block to the first virtual disk configured in thecache storage; by the media agent, serving the first data block from thefirst virtual disk to the first hypervisor in response to a first readrequest issued by the first virtual machine; and by the media agent,based on determining that storage space in the cache storage should bereclaimed by discarding data blocks from the cache storage, refrainingfrom discarding any data blocks from the cache storage that were writtenby the first virtual machine, including the first data block.
 12. Themethod of claim 11, further comprising: by the media agent, based ondetermining that storage space in the cache storage should be reclaimedby discarding data blocks from the cache storage, discarding from thecache storage a second data block that was not written by the firstvirtual machine and has been read from the block-level backup copy. 13.The method of claim 11, wherein the second hypervisor is one of: a sametype as the first hypervisor, and a different type as the firsthypervisor.
 14. The method of claim 11, further comprising: by the firsthypervisor, transmitting to the first virtual disk a second read requestissued by the first virtual machine for a second data block; by themedia agent, intercepting the second read request; based on determiningthat the second data block is not in the first virtual disk, by themedia agent: (i) reading the second data block from the block-levelbackup copy, and (ii) storing the second data block to the first virtualdisk and serving the second data block from the first virtual disk tothe first hypervisor in response to the second read request.
 15. Themethod of claim 14, wherein the first virtual machine executing on thefirst hypervisor uses the block-level backup copy of the second virtualmachine of the second hypervisor, without conversion of the metadatafrom the second hypervisor, which was not included in the block-levelbackup copy.
 16. The method of claim 11, further comprising: based ondetermining by the media agent that storage space in the cache storageshould be reclaimed, discarding from the cache storage a second datablock that was not written by the first virtual machine and has beenread from the block-level backup copy.
 17. The method of claim 11,further comprising: based on determining by the media agent that storagespace in the cache storage should be reclaimed, identifying by the mediaagent a second data block in the cache storage that is least recentlyused by the first virtual machine; and based on further determining bythe media agent that the second data block was not written by the firstvirtual machine and has been read from the block-level backup copy,discarding the second data block from the cache storage.
 18. The methodof claim 11, further comprising one of: before the first virtual machineis powered up, by the media agent, exporting the cache storage as aNetwork File System (NFS) mount point to the first hypervisor; andbefore the first virtual machine is powered up: by the media agent,exposing the cache storage as an Internet Small Computer SystemsInterface (iSCSI) target to the first hypervisor.
 19. The method ofclaim 11, wherein the first virtual machine executing on the firsthypervisor uses data blocks from the block-level backup copy of thesecond virtual machine without restoring the block-level backup copy inits entirety.
 20. The method of claim 11, wherein the powering up of thefirst virtual machine on the first hypervisor is caused, after the mediaagent associates the first virtual disk with the block-level backup copyof the second virtual machine, by one or more of: the media agent, and adata agent that also executes on the second computing device.